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JBO Thread Ring Gauge (GO) - UNC - Left Hand - 2A - 1/4 x 20
SKU:JBO-502408
The JBO Thread Ring Gauge GO for UNC Left-Hand 1/4 x 20 (2A) is a precision inspection tool designed to quickly verify external thread diameters and confirm conformance with UNC standards. It ser...
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Specification
| Thread Form | UNC |
| Size | 1/4 |
| Pitch | 20 |
| Gauge Type | Ring Gauge (GO) |
| Thread Direction | Left Hand |
| Tolerance | 2A |
£77.76
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 GO for UNC Left-Hand 1/4 x 20 (2A) is a precision inspection tool designed to quickly verify external thread diameters and confirm conformance with UNC standards. It serves engineers, machinists, inspectors, and quality teams across manufacturing and maintenance settings by delivering fast, reliable pass/fail checks on threaded components.
Manufactured from hardened steel for exceptional durability, this GO gauge withstands daily use in demanding work environments. Its simple, intuitive design makes it easy to identify properly conforming parts at a glance, supporting efficient quality control and precise engineering outcomes.
- Precise UNC Left-Hand Go Gauge (1/4 x 20, 2A): Quickly verify external thread diameter and conformance to UNC Left-Hand 1/4 x 20 2A standards, enabling consistent quality checks with minimal setup.
- Hardened Steel Construction: Built to resist wear, deliver long-lasting dimensional stability, and withstand the rigors of busy shops and production lines.
- Easy Conformance Identification: Intuitive, go/no-go style feedback helps operators spot compliant parts at a glance, speeding inspections and reducing rework in QC workflows.
By using this gauge, you streamline thread inspection, improve measurement confidence, and maintain tight control over assembly accuracy for UNC left-hand applications. Its durability and straightforward use translate to reduced downtime, fewer rejects, and more reliable, repeatable results across jobs that require 1/4 x 20 UNC threads.
| Thread Form | UNC |
| Size | 1/4 |
| Pitch | 20 |
| Gauge Type | Ring Gauge (GO) |
| 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 (GO) - Unified
View full collection →You are viewing JBO-502408. Click any other SKU to view its full details.
| Product SKU | Size | Pitch | Price | Stock | Order |
|---|---|---|---|---|---|
| JBO-502377 | No. 1 | 64 | £114.03 | 5 days | |
| JBO-502382 | No. 2 | 56 | £86.19 | 5 days | |
| JBO-502386 | No. 3 | 48 | £103.52 | 5 days | |
| JBO-502388 | No. 4 | 40 | £75.45 | 5 days | |
| JBO-502392 | No. 5 | 40 | £69.08 | 5 days | |
| JBO-502393 | No. 6 | 32 | £58.90 | 5 days | |
| JBO-502396 | No. 8 | 32 | £55.39 | 5 days | |
| JBO-502379 | No. 10 | 24 | £54.28 | 5 days | |
| JBO-505676 | No. 12 | 24 | £63.28 | 5 days | |
| JBO-502406 | 1/4 | 20 | £51.88 | 5 days | |
| JBO-502416 | 5/16 | 18 | £55.15 | 5 days | |
| JBO-502413 | 3/8 | 16 | £60.08 | 5 days | |
| JBO-502421 | 7/16 | 14 | £65.48 | 5 days | |
| JBO-502404 | 1/2 | 13 | £71.94 | 5 days | |
| JBO-502425 | 9/16 | 12 | £99.25 | 5 days | |
| JBO-502419 | 5/8 | 11 | £84.43 | 5 days | |
| JBO-502411 | 3/4 | 10 | £104.51 | 5 days | |
| JBO-502423 | 7/8 | 9 | £127.21 | 5 days | |
| JBO-502398 | 1 | 8 | £137.06 | 5 days | |
| JBO-502401 | 1 1/8 | 7 | £183.12 | 5 days | |
| JBO-502400 | 1 1/4 | 7 | £198.46 | 5 days | |
| JBO-502403 | 1 3/8 | 6 | £213.83 | 5 days | |
| JBO-502399 | 1 1/2 | 6 | £233.56 | 5 days | |
| JBO-502402 | 1 3/4 | 5 | £292.77 | 5 days | |
| JBO-502409 | 2 | 4.5 | £335.54 | 5 days | |
| JBO-502963 | 2 1/4 | 4.5 | £382.68 | 5 days | |
| JBO-502410 | 2 1/2 | 4 | £427.63 | 5 days | |
| JBO-507588 | 2 3/4 | 4 | £476.99 | 5 days | |
| JBO-502378 | No. 1 | 64 | £167.77 | 5 days | |
| JBO-502385 | No. 2 | 56 | £128.29 | 5 days | |
| JBO-502387 | No. 3 | 48 | £135.97 | 5 days | |
| JBO-502391 | No. 4 | 40 | £105.48 | 5 days | |
| JBO-502873 | No. 5 | 40 | £96.83 | 5 days | |
| JBO-502394 | No. 6 | 32 | £82.35 | 5 days | |
| JBO-502397 | No. 8 | 32 | £77.41 | 5 days | |
| JBO-502380 | No. 10 | 24 | £77.64 | 5 days | |
| JBO-502381 | No. 12 | 24 | £82.14 | 5 days | |
| JBO-502407 | 1/4 | 20 | £76.22 | 5 days | |
| JBO-502417 | 5/16 | 18 | £81.03 | 5 days | |
| JBO-502414 | 3/8 | 16 | £88.06 | 5 days | |
| JBO-502422 | 7/16 | 14 | £98.14 | 5 days | |
| JBO-502405 | 1/2 | 13 | £107.90 | 5 days | |
| JBO-503165 | 9/16 | 12 | £120.61 | 5 days | |
| JBO-502420 | 5/8 | 11 | £128.29 | 5 days | |
| JBO-502797 | 3/4 | 10 | £156.81 | In Stock | |
| JBO-502424 | 7/8 | 9 | £189.69 | 5 days | |
| JBO-503166 | 1 | 8 | £209.44 | 5 days | |
| JBO-506400 | No. 1 | 64 | £163.39 | 5 days | |
| JBO-506401 | No. 2 | 56 | £129.40 | 5 days | |
| JBO-506402 | No. 3 | 48 | £148.02 | 5 days | |
| JBO-504041 | No. 4 | 40 | £112.95 | 5 days | |
| JBO-506403 | No. 5 | 40 | £103.52 | 5 days | |
| JBO-502395 | No. 6 | 32 | £88.15 | 5 days | |
| JBO-506404 | No. 8 | 32 | £83.11 | 5 days | |
| JBO-503427 | No. 10 | 24 | £81.36 | 5 days | |
| JBO-505677 | No. 12 | 24 | £87.84 | 5 days | |
| JBO-502408 Viewing | 1/4 | 20 | £77.76 | 5 days | |
| JBO-502418 | 5/16 | 18 | £82.80 | 5 days | |
| JBO-502415 | 3/8 | 16 | £90.25 | 5 days | |
| JBO-506405 | 7/16 | 14 | £98.14 | 5 days | |
| JBO-506406 | 1/2 | 13 | £107.90 | 5 days | |
| JBO-506407 | 9/16 | 12 | £118.42 | 5 days | |
| JBO-504042 | 5/8 | 11 | £130.48 | 5 days | |
| JBO-502412 | 3/4 | 10 | £156.81 | 5 days | |
| JBO-506408 | 7/8 | 9 | £189.69 | 5 days | |
| JBO-504043 | 1 | 8 | £209.44 | 5 days | |
| JBO-506409 | 1 1/8 | 7 | £245.62 | 5 days | |
| JBO-505756 | 1 1/4 | 7 | £268.65 | 5 days | |
| JBO-506410 | 1 3/8 | 6 | £299.34 | 5 days | |
| JBO-506411 | 1 1/2 | 6 | £317.99 | 5 days | |
| JBO-502426 | No. 1 | 72 | £126.10 | 5 days | |
| JBO-502436 | No. 2 | 64 | £105.26 | 5 days | |
| JBO-502438 | No. 3 | 56 | £104.95 | 5 days | |
| JBO-502440 | No. 4 | 48 | £92.98 | 5 days | |
| JBO-502442 | No. 5 | 44 | £74.55 | 5 days | |
| JBO-502444 | No. 6 | 40 | £71.72 | 5 days | |
| JBO-502446 | No. 8 | 36 | £66.35 | 5 days | |
| JBO-502430 | No. 10 | 32 | £52.75 | 5 days | |
| JBO-502433 | No. 12 | 28 | £63.28 | 5 days | |
| JBO-502458 | 1/4 | 28 | £51.97 | 5 days | |
| JBO-502469 | 5/16 | 24 | £55.15 | 5 days | |
| JBO-502466 | 3/8 | 24 | £60.08 | 5 days | |
| JBO-502475 | 7/16 | 20 | £64.82 | 5 days | |
| JBO-502455 | 1/2 | 20 | £71.94 | 5 days | |
| JBO-502481 | 9/16 | 18 | £77.41 | 5 days | |
| JBO-502472 | 5/8 | 18 | £85.65 | 5 days | |
| JBO-502461 | 3/4 | 16 | £99.68 | 5 days | |
| JBO-502478 | 7/8 | 14 | £117.33 | 5 days | |
| JBO-502448 | 1 | 12 | £131.59 | 5 days | |
| JBO-502453 | 1 1/8 | 12 | £148.02 | 5 days | |
| JBO-502452 | 1 1/4 | 12 | £161.19 | 5 days | |
| JBO-502454 | 1 3/8 | 12 | £175.43 | 5 days | |
| JBO-502451 | 1 1/2 | 12 | £186.41 | 5 days | |
| JBO-502427 | No. 0 | 80 | £176.54 | 5 days | |
| JBO-502429 | No. 1 | 72 | £148.02 | 5 days | |
| JBO-502437 | No. 2 | 64 | £137.06 | 5 days | |
| JBO-502439 | No. 3 | 56 | £135.97 | 5 days | |
| JBO-502441 | No. 4 | 48 | £121.72 | 5 days | |
| JBO-502443 | No. 5 | 44 | £96.83 | 5 days | |
| JBO-502445 | No. 6 | 40 | £93.10 | 5 days | |
| JBO-502447 | No. 8 | 36 | £85.65 | 5 days | |
| JBO-502431 | No. 10 | 32 | £73.58 | 5 days | |
| JBO-502435 | No. 12 | 28 | £82.14 | 5 days | |
| JBO-502459 | 1/4 | 28 | £72.81 | 5 days | |
| JBO-502470 | 5/16 | 24 | £77.10 | 5 days | |
| JBO-502467 | 3/8 | 24 | £84.22 | 5 days | |
| JBO-502476 | 7/16 | 20 | £90.46 | 5 days | |
| JBO-502456 | 1/2 | 20 | £100.55 | 5 days | |
| JBO-502482 | 9/16 | 18 | £108.45 | 5 days | |
| JBO-502473 | 5/8 | 18 | £119.52 | 5 days | |
| JBO-502463 | 3/4 | 16 | £139.25 | 5 days | |
| JBO-502479 | 7/8 | 14 | £164.47 | 5 days | |
| JBO-502449 | 1 | 12 | £183.12 | 5 days | |
| JBO-502757 | 1 1/8 | 12 | £207.25 | 5 days | |
| JBO-503207 | 1 1/4 | 12 | £225.87 | 5 days | |
| JBO-503209 | 1 3/8 | 12 | £245.62 | 5 days | |
| JBO-502768 | 1 1/2 | 12 | £264.27 | 5 days | |
| JBO-506438 | No. 0 | 80 | £176.54 | 5 days | |
| JBO-506441 | No. 1 | 72 | £148.02 | 5 days | |
| JBO-506445 | No. 2 | 64 | £137.06 | 5 days | |
| JBO-506448 | No. 3 | 56 | £135.97 | 5 days | |
| JBO-506449 | No. 4 | 48 | £121.72 | 5 days | |
| JBO-506452 | No. 5 | 44 | £96.83 | 5 days | |
| JBO-506453 | No. 6 | 40 | £93.10 | 5 days | |
| JBO-506454 | No. 8 | 36 | £85.65 | 5 days | |
| JBO-502432 | No. 10 | 32 | £76.44 | 5 days | |
| JBO-506455 | No. 12 | 28 | £83.67 | 5 days | |
| JBO-502460 | 1/4 | 28 | £72.81 | 5 days | |
| JBO-502471 | 5/16 | 24 | £81.03 | 5 days | |
| JBO-502468 | 3/8 | 24 | £84.22 | 5 days | |
| JBO-502477 | 7/16 | 20 | £92.98 | 5 days | |
| JBO-502457 | 1/2 | 20 | £104.72 | 5 days | |
| JBO-502483 | 9/16 | 18 | £116.23 | 5 days | |
| JBO-502474 | 5/8 | 18 | £119.52 | 5 days | |
| JBO-502464 | 3/4 | 16 | £139.25 | 5 days | |
| JBO-502480 | 7/8 | 14 | £164.47 | 5 days | |
| JBO-502450 | 1 | 12 | £183.12 | 5 days | |
| JBO-503127 | 1 1/8 | 12 | £207.25 | 5 days | |
| JBO-506456 | 1 1/4 | 12 | £225.87 | 5 days | |
| JBO-506457 | 1 3/8 | 12 | £245.62 | 5 days | |
| JBO-505736 | 1 1/2 | 12 | £264.27 | 5 days | |
| JBO-501299 | No. 12 | 32 | £74.79 | 5 days | |
| JBO-501313 | 1/4 | 32 | £74.79 | 5 days | |
| JBO-501326 | 5/16 | 32 | £80.16 | 5 days | |
| JBO-501323 | 3/8 | 32 | £85.20 | 5 days | |
| JBO-501329 | 7/16 | 2 | £90.46 | 5 days | |
| JBO-501310 | 1/2 | 28 | £94.52 | 5 days | |
| JBO-501334 | 9/16 | 24 | £104.60 | 5 days | |
| JBO-501327 | 5/8 | 24 | £111.84 | 5 days | |
| JBO-501316 | 11/16 | 24 | £120.61 | 5 days | |
| JBO-501319 | 3/4 | 20 | £127.21 | 5 days | |
| JBO-501317 | 13/16 | 20 | £133.78 | 5 days | |
| JBO-501333 | 7/8 | 20 | £144.74 | 5 days | |
| JBO-501318 | 15/16 | 20 | £155.70 | 5 days | |
| JBO-501300 | 1 | 20 | £163.39 | 5 days | |
| JBO-501305 | 1 1/16 | 18 | £173.24 | 5 days | |
| JBO-501303 | 1 1/8 | 18 | £179.84 | 5 days | |
| JBO-501307 | 1 3/16 | 18 | £189.69 | 5 days | |
| JBO-501302 | 1 1/4 | 18 | £202.87 | 5 days | |
| JBO-501308 | 1 5/16 | 18 | £213.83 | 5 days | |
| JBO-501306 | 1 3/8 | 18 | £225.87 | 5 days | |
| JBO-501309 | 1 7/16 | 18 | £236.85 | 5 days | |
| JBO-501301 | 1 1/2 | 18 | £248.90 | 5 days | |
| JBO-506769 | 1 9/16 | 18 | £266.46 | 5 days | |
| JBO-506489 | No. 12 | 32 | £105.71 | 5 days | |
| JBO-501315 | 1/4 | 32 | £105.71 | 5 days | |
| JBO-506490 | 5/16 | 32 | £116.23 | 5 days | |
| JBO-506491 | 3/8 | 32 | £121.72 | 5 days | |
| JBO-501332 | 7/16 | 2 | £127.21 | 5 days | |
| JBO-503778 | 1/2 | 28 | £133.78 | 5 days | |
| JBO-505871 | 9/16 | 24 | £145.83 | 5 days | |
| JBO-503138 | 5/8 | 24 | £167.77 | 5 days | |
| JBO-506492 | 11/16 | 24 | £178.73 | 5 days | |
| JBO-501322 | 3/4 | 20 | £188.61 | 5 days | |
| JBO-506493 | 13/16 | 20 | £202.87 | 5 days | |
| JBO-506494 | 7/8 | 20 | £218.21 | 5 days | |
| JBO-506495 | 15/16 | 20 | £233.56 | 5 days | |
| JBO-504056 | 1 | 20 | £244.52 | 5 days | |
| JBO-502570 | 1/4 | 36 | £207.25 | 5 days | |
| JBO-502546 | 1 | 32 | £421.06 | 5 days | |
| JBO-502576 | 11/16 | 16 | £350.89 | 5 days | |
| JBO-502580 | 13/16 | 16 | £307.02 | 5 days | |
| JBO-502601 | 7/8 | 16 | £313.60 | 5 days | |
| JBO-502545 | 1 | 16 | £350.89 | 5 days | |
| JBO-542688 | 1 1/16 | 16 | £370.62 | 5 days | |
| JBO-502561 | 1 3/16 | 16 | £407.90 | 5 days | |
| JBO-505372 | 1 | 14 | £288.38 | 5 days | |
| JBO-502552 | 1 1/16 | 12 | £321.28 | 5 days | |
| JBO-502560 | 1 3/16 | 12 | £364.04 | 5 days | |
| JBO-502563 | 1 5/16 | 12 | £359.66 | 5 days | |
| JBO-502562 | 1 5/8 | 12 | £459.45 | 5 days | |
| JBO-502554 | 1 3/4 | 12 | £441.89 | 5 days | |
| JBO-502565 | 1 7/8 | 12 | £482.48 | 5 days | |
| JBO-502584 | 2 | 12 | £490.14 | 5 days | |
| JBO-503417 | 1 1/8 | 8 | £357.46 | 5 days | |
| JBO-502549 | 1 1/4 | 8 | £359.66 | 5 days | |
| JBO-552099 | 1 3/8 | 8 | £387.07 | 5 days | |
| JBO-502547 | 1 1/2 | 8 | £463.83 | 5 days | |
| JBO-502924 | 1 5/8 | 8 | £486.86 | 5 days | |
| JBO-502556 | 1 3/4 | 8 | £552.65 | 5 days | |
| JBO-503356 | 2 | 8 | £596.51 | 5 days | |
| JBO-504210 | No. 2 | 56 | £167.77 | 5 days | |
| JBO-503593 | No. 4 | 40 | £139.25 | 5 days | |
| JBO-505569 | No. 6 | 32 | £120.61 | 5 days | |
| JBO-501415 | No. 8 | 32 | £111.84 | 5 days | |
| JBO-547026 | No. 10 | 24 | £111.84 | 5 days | |
| JBO-547027 | 1/4 | 20 | £111.84 | 5 days | |
| JBO-547028 | 5/16 | 18 | £111.84 | 5 days | |
| JBO-507449 | 3/8 | 16 | £116.23 | 5 days | |
| JBO-554996 | 7/16 | 14 | £148.02 | 5 days | |
| JBO-547029 | No. 4 | 48 | £143.64 | 5 days | |
| JBO-505347 | No. 6 | 40 | £117.33 | 5 days | |
| JBO-501418 | No. 8 | 36 | £108.02 | 5 days | |
| JBO-501417 | No. 10 | 32 | £94.30 | 5 days | |
| JBO-504244 | No. 12 | 28 | £108.02 | 5 days | |
| JBO-501419 | 1/4 | 28 | £94.30 | 5 days | |
| JBO-501422 | 5/16 | 24 | £98.80 | 5 days | |
| JBO-501421 | 3/8 | 24 | £106.58 | 5 days | |
| JBO-501424 | 7/16 | 20 | £116.23 | 5 days | |
| JBO-502986 | 1/2 | 20 | £128.29 | 5 days | |
| JBO-501425 | 9/16 | 18 | £135.97 | 5 days | |
| JBO-501423 | 5/8 | 18 | £153.51 | 5 days | |
| JBO-501420 | 3/4 | 16 | £176.54 | 5 days | |
| JBO-503651 | 7/8 | 14 | £207.25 | 5 days | |
| JBO-503703 | 1 | 12 | £233.56 | 5 days | |
| JBO-547575 | 1/4 | 28 | £151.32 | 5 days | |
| JBO-503866 | 3/8 | 24 | £171.05 | 5 days | |
| JBO-547590 | 1/2 | 20 | £206.14 | 5 days |
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