Please log in here to access all benefits, including promotional discounts and faster checkouts.
JBO Thread Ring Gauge (NoGo) - UNJF - Left Hand - 2A - 1/2 x 20
SKU:JBO-544329
The JBO Thread Ring Gauge (NoGo) – UNJF – Left Hand – 2A – 1/2 x 20 is a precision tool designed to verify external thread diameters against Unified thread standards. It’s ideal for a wide audien...
Read more ↓
Specification
| Thread Form | UNJF |
| Size | 1/2 |
| Pitch | 20 |
| Gauge Type | Ring Gauge (NoGo) |
| Thread Direction | Left Hand |
| Tolerance | 2A |
£206.14
Prices shown ex. VAT
5 days estimated lead time
— subject to availability
View Other Sizes →
Free delivery over £50 ex VAT
Secure checkout
14-day returns
30+ years expertise
Pay in 3 interest-free instalments. No extra cost if paid on time. 18+ only.
Learn more about Klarna
Learn more about Klarna
The JBO Thread Ring Gauge (NoGo) – UNJF – Left Hand – 2A – 1/2 x 20 is a precision tool designed to verify external thread diameters against Unified thread standards. It’s ideal for a wide audience—from engineers and inspectors to machinists and procurement teams—providing quick, reliable checks to ensure threaded components will fit as intended.
This NoGo gauge features a left-hand UNJF thread form in the 2A class and 1/2 x 20 size, with a rugged hardened steel construction built to withstand everyday workshop use. The NoGo design makes non-conforming threads easy to identify, helping you maintain quality and reduce rework across production and inspection processes.
- NoGo design for fast conformity checks: Quickly identifies non-conforming threads, speeding inspections and reducing guesswork or back-and-forth rechecks.
- UNJF Left-Hand, 2A, 1/2 x 20 sizing: Precisely matched to the UNJF left-hand thread standard in class 2A and size 1/2 x 20, ensuring accurate external thread diameter verification.
- Hardened steel construction: Delivers durability and long service life in demanding environments while maintaining measurement reliability over time.
Used in manufacturing, automotive, and aerospace settings, this gauge helps you confirm thread conformity on first pass, protect against mismatched fittings, and keep your quality control workflow efficient. Its robust build and exacting NoGo specification give you confidence that threaded components will assemble correctly and perform as intended, day after day.
| Thread Form | UNJF |
| Size | 1/2 |
| Pitch | 20 |
| Gauge Type | Ring Gauge (NoGo) |
| Thread Direction | Left Hand |
| Tolerance | 2A |
What time are Protool open?
We are open Monday to Friday between 8:30am and 5pm.
Do you offer Free Next Day delivery?
Yes! We offer Free Next Day delivery via Royal Mail Tracked 24 on all orders over £50 ex VAT*. We also offer Free DPD Local Next Day delivery on all orders over £100 ex VAT*.
We also offer the following:
- Royal Mail Tracked 24 — £5.90 (FREE on orders over £50 ex VAT*). Order before 4:30pm for next day delivery. No signature required.
- DPD Local Next Day — £8.00 (FREE on orders over £100 ex VAT*). Standard next day delivery to UK mainland addresses.
- Royal Mail Special Delivery — £12.50. Guaranteed delivery before 1pm the next working day.
- DPD Saturday Delivery — £25.00. Must be ordered on Friday before 4pm. Pre-12pm delivery.
For delivery to Scottish Highlands & Islands, Northern Ireland, Republic of Ireland, or overseas locations, additional charges apply. Please see our delivery page for full details, or call us on 01732 887 334.
*T's & C's and exclusions apply. Please see our delivery page for more information on all our services.
★★★★★
Nice experience staff are very helpful and interested...
Staff are very helpful and interested in providing a good service making us the customer feel valued.
★★★★★
first place we look
honest about stock and prices are competitive.
★★★★★
Polite and helpful
Staff are very helpful and polite.Goods that were in stock were dispatched same day and back orders were quick in coming through .
★★★★★
Buying experience
Phone requests are handled quickly and without any fuss. The website is easy to use and straightforward to order from. It’s especially helpful that it shows real‑time availability, so we don’t need to call to confirm whether parts will arrive.
Full Range: JBO Thread Ring Gauges (NoGo) - Unified
View full collection →You are viewing JBO-544329. Click any other SKU to view its full details.
| Product SKU | Size | Pitch | Price | Stock | Order |
|---|---|---|---|---|---|
| JBO-501051 | No. 1 | 64 | £114.03 | 5 days | |
| JBO-501057 | No. 2 | 56 | £86.19 | 5 days | |
| JBO-501061 | No. 3 | 48 | £103.52 | 5 days | |
| JBO-501063 | No. 4 | 40 | £75.45 | 5 days | |
| JBO-501066 | No. 5 | 40 | £69.08 | 5 days | |
| JBO-501067 | No. 6 | 32 | £58.90 | 5 days | |
| JBO-501070 | No. 8 | 32 | £55.39 | 5 days | |
| JBO-501053 | No. 10 | 24 | £54.28 | 5 days | |
| JBO-501055 | No. 12 | 24 | £63.28 | 5 days | |
| JBO-501080 | 1/4 | 20 | £51.88 | 5 days | |
| JBO-501088 | 5/16 | 18 | £55.15 | 5 days | |
| JBO-501085 | 3/8 | 16 | £60.08 | 5 days | |
| JBO-501093 | 7/16 | 14 | £65.48 | 5 days | |
| JBO-501078 | 1/2 | 13 | £71.94 | 5 days | |
| JBO-501097 | 9/16 | 12 | £99.25 | 5 days | |
| JBO-501091 | 5/8 | 11 | £84.43 | 5 days | |
| JBO-501083 | 3/4 | 10 | £104.51 | 5 days | |
| JBO-501095 | 7/8 | 9 | £127.21 | 5 days | |
| JBO-501072 | 1 | 8 | £137.06 | 5 days | |
| JBO-501075 | 1 1/8 | 7 | £183.12 | 5 days | |
| JBO-501074 | 1 1/4 | 7 | £198.46 | 5 days | |
| JBO-501077 | 1 3/8 | 6 | £213.83 | 5 days | |
| JBO-501073 | 1 1/2 | 6 | £233.56 | 5 days | |
| JBO-501076 | 1 3/4 | 5 | £292.77 | 5 days | |
| JBO-503352 | 2 | 4.5 | £335.54 | 5 days | |
| JBO-502964 | 2 1/4 | 4.5 | £382.68 | 5 days | |
| JBO-541018 | 2 1/2 | 4 | £427.63 | 5 days | |
| JBO-507589 | 2 3/4 | 4 | £476.99 | 5 days | |
| JBO-501052 | No. 1 | 64 | £167.77 | 5 days | |
| JBO-501060 | No. 2 | 56 | £128.29 | 5 days | |
| JBO-501062 | No. 3 | 48 | £135.97 | 5 days | |
| JBO-501065 | No. 4 | 40 | £105.48 | 5 days | |
| JBO-502874 | No. 5 | 40 | £96.83 | 5 days | |
| JBO-501068 | No. 6 | 32 | £82.35 | 5 days | |
| JBO-501071 | No. 8 | 32 | £77.41 | 5 days | |
| JBO-501054 | No. 10 | 24 | £77.64 | 5 days | |
| JBO-501056 | No. 12 | 24 | £82.14 | 5 days | |
| JBO-501081 | 1/4 | 20 | £76.22 | 5 days | |
| JBO-501089 | 5/16 | 18 | £81.03 | 5 days | |
| JBO-501086 | 3/8 | 16 | £88.06 | 5 days | |
| JBO-501094 | 7/16 | 14 | £98.14 | 5 days | |
| JBO-501079 | 1/2 | 13 | £107.90 | 5 days | |
| JBO-503178 | 9/16 | 12 | £120.61 | 5 days | |
| JBO-501092 | 5/8 | 11 | £128.29 | 5 days | |
| JBO-502798 | 3/4 | 10 | £156.81 | 5 days | |
| JBO-501096 | 7/8 | 9 | £189.69 | 5 days | |
| JBO-503179 | 1 | 8 | £209.44 | 5 days | |
| JBO-506412 | No. 1 | 64 | £163.39 | 5 days | |
| JBO-506413 | No. 2 | 56 | £129.40 | 5 days | |
| JBO-506414 | No. 3 | 48 | £148.02 | 5 days | |
| JBO-504045 | No. 4 | 40 | £112.95 | 5 days | |
| JBO-506415 | No. 5 | 40 | £103.52 | 5 days | |
| JBO-501069 | No. 6 | 32 | £88.15 | 5 days | |
| JBO-506416 | No. 8 | 32 | £83.11 | 5 days | |
| JBO-503428 | No. 10 | 24 | £81.36 | 5 days | |
| JBO-505540 | No. 12 | 24 | £87.84 | 5 days | |
| JBO-501082 | 1/4 | 20 | £77.76 | 5 days | |
| JBO-501090 | 5/16 | 18 | £82.80 | 5 days | |
| JBO-501087 | 3/8 | 16 | £90.25 | 5 days | |
| JBO-506417 | 7/16 | 14 | £98.14 | 5 days | |
| JBO-506418 | 1/2 | 13 | £107.90 | 5 days | |
| JBO-506420 | 9/16 | 12 | £118.42 | 5 days | |
| JBO-504046 | 5/8 | 11 | £130.48 | 5 days | |
| JBO-501084 | 3/4 | 10 | £156.81 | 5 days | |
| JBO-506422 | 7/8 | 9 | £189.69 | 5 days | |
| JBO-506423 | 1 | 8 | £209.44 | 5 days | |
| JBO-506424 | 1 1/8 | 7 | £245.62 | 5 days | |
| JBO-506426 | 1 1/4 | 7 | £268.65 | 5 days | |
| JBO-506428 | 1 3/8 | 6 | £299.34 | 5 days | |
| JBO-506430 | 1 1/2 | 6 | £317.99 | 5 days | |
| JBO-501099 | No. 0 | 80 | £126.10 | 5 days | |
| JBO-501101 | No. 1 | 72 | £105.38 | 5 days | |
| JBO-501108 | No. 2 | 64 | £105.26 | 5 days | |
| JBO-501110 | No. 3 | 56 | £104.95 | 5 days | |
| JBO-501112 | No. 4 | 48 | £92.98 | 5 days | |
| JBO-501114 | No. 5 | 44 | £74.55 | 5 days | |
| JBO-501116 | No. 6 | 40 | £71.72 | 5 days | |
| JBO-501118 | No. 8 | 36 | £66.35 | 5 days | |
| JBO-501103 | No. 10 | 32 | £52.75 | 5 days | |
| JBO-501106 | No. 12 | 28 | £63.28 | 5 days | |
| JBO-501130 | 1/4 | 28 | £51.97 | 5 days | |
| JBO-501140 | 5/16 | 24 | £55.15 | 5 days | |
| JBO-501137 | 3/8 | 24 | £60.08 | 5 days | |
| JBO-501146 | 7/16 | 20 | £64.82 | 5 days | |
| JBO-501127 | 1/2 | 20 | £71.94 | 5 days | |
| JBO-501152 | 9/16 | 18 | £77.41 | 5 days | |
| JBO-501143 | 5/8 | 18 | £85.65 | 5 days | |
| JBO-501133 | 3/4 | 16 | £99.68 | 5 days | |
| JBO-501149 | 7/8 | 14 | £117.33 | 5 days | |
| JBO-501120 | 1 | 12 | £131.59 | 5 days | |
| JBO-501125 | 1 1/8 | 12 | £148.02 | 5 days | |
| JBO-501124 | 1 1/4 | 12 | £161.19 | 5 days | |
| JBO-501126 | 1 3/8 | 12 | £175.43 | 5 days | |
| JBO-501123 | 1 1/2 | 12 | £186.41 | 5 days | |
| JBO-501100 | No. 0 | 80 | £176.54 | 5 days | |
| JBO-501102 | No. 1 | 72 | £148.02 | 5 days | |
| JBO-501109 | No. 2 | 64 | £137.06 | 5 days | |
| JBO-501111 | No. 3 | 56 | £135.97 | 5 days | |
| JBO-501113 | No. 4 | 48 | £121.72 | 5 days | |
| JBO-501115 | No. 5 | 44 | £96.83 | 5 days | |
| JBO-501117 | No. 6 | 40 | £93.10 | 5 days | |
| JBO-501119 | No. 8 | 36 | £85.65 | 5 days | |
| JBO-501104 | No. 10 | 32 | £73.58 | 5 days | |
| JBO-501107 | No. 12 | 28 | £82.14 | 5 days | |
| JBO-501131 | 1/4 | 28 | £72.81 | 5 days | |
| JBO-501141 | 5/16 | 24 | £77.10 | 5 days | |
| JBO-501138 | 3/8 | 24 | £84.22 | 5 days | |
| JBO-501147 | 7/16 | 20 | £90.46 | 5 days | |
| JBO-501128 | 1/2 | 20 | £100.55 | 5 days | |
| JBO-501153 | 9/16 | 18 | £108.45 | 5 days | |
| JBO-501144 | 5/8 | 18 | £119.52 | 5 days | |
| JBO-501134 | 3/4 | 16 | £139.25 | 5 days | |
| JBO-501150 | 7/8 | 14 | £164.47 | 5 days | |
| JBO-501121 | 1 | 12 | £183.12 | 5 days | |
| JBO-502758 | 1 1/8 | 12 | £207.25 | 5 days | |
| JBO-503208 | 1 1/4 | 12 | £225.87 | 5 days | |
| JBO-503210 | 1 3/8 | 12 | £245.62 | 5 days | |
| JBO-502767 | 1 1/2 | 12 | £264.27 | 5 days | |
| JBO-506458 | No. 0 | 80 | £176.54 | 5 days | |
| JBO-506460 | No. 1 | 72 | £148.02 | 5 days | |
| JBO-506461 | No. 2 | 64 | £137.06 | 5 days | |
| JBO-506462 | No. 3 | 56 | £135.97 | 5 days | |
| JBO-506463 | No. 4 | 48 | £121.72 | 5 days | |
| JBO-506465 | No. 5 | 44 | £96.83 | 5 days | |
| JBO-506466 | No. 6 | 40 | £93.10 | 5 days | |
| JBO-506468 | No. 8 | 36 | £85.65 | 5 days | |
| JBO-501105 | No. 10 | 32 | £76.44 | 5 days | |
| JBO-506470 | No. 12 | 28 | £83.67 | 5 days | |
| JBO-501132 | 1/4 | 28 | £72.81 | 5 days | |
| JBO-501142 | 5/16 | 24 | £81.03 | 5 days | |
| JBO-501139 | 3/8 | 24 | £84.22 | 5 days | |
| JBO-501148 | 7/16 | 20 | £92.98 | 5 days | |
| JBO-501129 | 1/2 | 20 | £104.72 | 5 days | |
| JBO-501154 | 9/16 | 18 | £116.23 | 5 days | |
| JBO-501145 | 5/8 | 18 | £119.52 | 5 days | |
| JBO-501135 | 3/4 | 16 | £139.25 | 5 days | |
| JBO-501151 | 7/8 | 14 | £164.47 | 5 days | |
| JBO-501122 | 1 | 12 | £183.12 | 5 days | |
| JBO-503126 | 1 1/8 | 12 | £207.25 | 5 days | |
| JBO-506473 | 1 1/4 | 12 | £225.87 | 5 days | |
| JBO-506476 | 1 3/8 | 12 | £245.62 | 5 days | |
| JBO-502851 | 1 1/2 | 12 | £264.27 | 5 days | |
| JBO-500006 | No. 12 | 32 | £74.79 | 5 days | |
| JBO-500019 | 1/4 | 32 | £74.79 | 5 days | |
| JBO-500033 | 5/16 | 32 | £80.16 | 5 days | |
| JBO-500029 | 3/8 | 32 | £85.20 | 5 days | |
| JBO-500036 | 7/16 | 2 | £90.46 | 5 days | |
| JBO-500016 | 1/2 | 28 | £94.52 | 5 days | |
| JBO-500040 | 9/16 | 24 | £104.60 | 5 days | |
| JBO-500034 | 5/8 | 24 | £111.84 | 5 days | |
| JBO-500022 | 11/16 | 24 | £120.61 | 5 days | |
| JBO-500025 | 3/4 | 20 | £127.21 | 5 days | |
| JBO-500023 | 13/16 | 20 | £133.78 | 5 days | |
| JBO-500039 | 7/8 | 20 | £144.74 | 5 days | |
| JBO-500024 | 15/16 | 20 | £155.70 | 5 days | |
| JBO-500007 | 1 | 20 | £163.39 | 5 days | |
| JBO-500011 | 1 1/16 | 18 | £173.24 | 5 days | |
| JBO-505428 | 1 1/8 | 18 | £179.84 | 5 days | |
| JBO-500013 | 1 3/16 | 18 | £189.69 | 5 days | |
| JBO-500009 | 1 1/4 | 18 | £202.87 | 5 days | |
| JBO-500014 | 1 5/16 | 18 | £213.83 | 5 days | |
| JBO-500012 | 1 3/8 | 18 | £225.87 | 5 days | |
| JBO-500015 | 1 7/16 | 18 | £236.85 | 5 days | |
| JBO-500008 | 1 1/2 | 18 | £248.90 | 5 days | |
| JBO-503813 | 1 9/16 | 18 | £266.46 | 5 days | |
| JBO-506504 | No. 12 | 32 | £105.71 | 5 days | |
| JBO-500021 | 1/4 | 32 | £105.71 | 5 days | |
| JBO-506505 | 5/16 | 32 | £116.23 | 5 days | |
| JBO-506506 | 3/8 | 32 | £121.72 | 5 days | |
| JBO-500038 | 7/16 | 2 | £127.21 | 5 days | |
| JBO-503779 | 1/2 | 28 | £133.78 | 5 days | |
| JBO-505872 | 9/16 | 24 | £145.83 | 5 days | |
| JBO-503137 | 5/8 | 24 | £167.77 | 5 days | |
| JBO-506507 | 11/16 | 24 | £178.73 | 5 days | |
| JBO-500028 | 3/4 | 20 | £188.61 | 5 days | |
| JBO-506508 | 13/16 | 20 | £202.87 | 5 days | |
| JBO-506509 | 7/8 | 20 | £218.21 | 5 days | |
| JBO-506510 | 15/16 | 20 | £233.56 | 5 days | |
| JBO-504057 | 1 | 20 | £244.52 | 5 days | |
| JBO-501232 | 1/4 | 36 | £207.25 | 5 days | |
| JBO-501205 | 1 | 32 | £421.06 | 5 days | |
| JBO-501237 | 11/16 | 16 | £350.89 | 5 days | |
| JBO-501240 | 13/16 | 16 | £307.02 | 5 days | |
| JBO-501259 | 7/8 | 16 | £313.60 | 5 days | |
| JBO-501204 | 1 | 16 | £350.89 | 5 days | |
| JBO-540054 | 1 1/16 | 16 | £370.62 | 5 days | |
| JBO-501223 | 1 3/16 | 16 | £407.90 | 5 days | |
| JBO-501202 | 1 | 14 | £288.38 | 5 days | |
| JBO-501214 | 1 1/16 | 12 | £321.28 | 5 days | |
| JBO-501222 | 1 3/16 | 12 | £364.04 | 5 days | |
| JBO-501225 | 1 5/16 | 12 | £359.66 | 5 days | |
| JBO-502756 | 1 5/8 | 12 | £459.45 | 5 days | |
| JBO-501216 | 1 3/4 | 12 | £441.89 | 5 days | |
| JBO-501227 | 1 7/8 | 12 | £482.48 | 5 days | |
| JBO-502835 | 2 | 12 | £490.14 | 5 days | |
| JBO-501213 | 1 1/8 | 8 | £357.46 | 5 days | |
| JBO-501209 | 1 1/4 | 8 | £359.66 | 5 days | |
| JBO-501221 | 1 3/8 | 8 | £387.07 | 5 days | |
| JBO-501207 | 1 1/2 | 8 | £463.83 | 5 days | |
| JBO-501224 | 1 5/8 | 8 | £486.86 | 5 days | |
| JBO-501218 | 1 3/4 | 8 | £552.65 | 5 days | |
| JBO-503355 | 2 | 8 | £596.51 | 5 days | |
| JBO-504211 | No. 2 | 56 | £167.77 | 5 days | |
| JBO-503594 | No. 4 | 40 | £139.25 | 5 days | |
| JBO-500119 | No. 6 | 32 | £120.61 | 5 days | |
| JBO-500120 | No. 8 | 32 | £111.84 | 5 days | |
| JBO-544018 | No. 10 | 24 | £111.84 | 5 days | |
| JBO-544019 | 1/4 | 20 | £111.84 | 5 days | |
| JBO-544020 | 5/16 | 18 | £111.84 | 5 days | |
| JBO-544021 | 3/8 | 16 | £116.23 | 5 days | |
| JBO-554997 | 7/16 | 14 | £148.02 | 5 days | |
| JBO-544022 | No. 4 | 48 | £143.64 | 5 days | |
| JBO-505348 | No. 6 | 40 | £117.33 | 5 days | |
| JBO-500123 | No. 8 | 36 | £108.02 | 5 days | |
| JBO-500122 | No. 10 | 32 | £94.30 | 5 days | |
| JBO-504245 | No. 12 | 28 | £108.02 | 5 days | |
| JBO-500125 | 1/4 | 28 | £94.30 | 5 days | |
| JBO-500127 | 5/16 | 24 | £98.80 | 5 days | |
| JBO-500126 | 3/8 | 24 | £106.58 | 5 days | |
| JBO-500129 | 7/16 | 20 | £116.23 | 5 days | |
| JBO-502985 | 1/2 | 20 | £128.29 | 5 days | |
| JBO-500130 | 9/16 | 18 | £135.97 | 5 days | |
| JBO-500128 | 5/8 | 18 | £153.51 | 5 days | |
| JBO-503100 | 3/4 | 16 | £176.54 | 5 days | |
| JBO-503652 | 7/8 | 14 | £207.25 | 5 days | |
| JBO-500124 | 1 | 12 | £233.56 | 5 days | |
| JBO-544318 | 1/4 | 28 | £151.32 | 5 days | |
| JBO-504653 | 5/16 | 24 | £159.00 | 5 days | |
| JBO-503867 | 3/8 | 24 | £171.05 | 5 days | |
| JBO-544329 Viewing | 1/2 | 20 | £206.14 | 5 days | |
| JBO-503729 | 3/4 | 16 | £248.90 | 5 days |
No products match your filters.
