Please log in here to access all benefits, including promotional discounts and faster checkouts.

Asimeto Ring Thread Gauge (Go) - Metric - Right Hand - 6g - M21 x 1
| Thread Form | Metric |
| Size | M21 |
| Pitch | 1 |
| Gauge Type | Ring Gauge (GO) |
Learn more about Klarna
Compatible certification
The ones our customers buy most.Description
The Asimeto Ring Gauge GO Metric Fine 6g (685 Series, Right Hand, M21 x 1) is a precision tool designed for quality control and manufacturing teams that need fast, reliable verification of cylindrical thread sizes. Built for use with metric fine 6g threads, this GO gauge helps ensure parts meet exact specifications on every production run.
- GO Ring Gauge for Metric Fine 6g threads: precisely checks minimum tolerances on M21 x 1 cylindrical parts.
- Right-Hand configuration: designed for standard right-hand thread components and assemblies.
- 685 Series GO gauge: part of the durable 685 Series, optimized for repeated shop-floor use.
- Material: manufactured from high-quality steel for strength and long life in demanding environments.
- Thread compatibility: engineered specifically for Metric Fine 6g thread standards common in automotive, aerospace, and general engineering.
This gauge streamlines go/no-go inspections, delivering quick, repeatable measurements that reduce rework and scrap. Its robust steel construction stands up to daily handling on busy shop floors, while the metric fine 6g compatibility ensures consistent fits across assemblies. Ideal for automotive, aerospace, and engineering QC workflows, the Asimeto GO gauge helps teams maintain tight dimensional control and trust in every part produced.
Part Numbers
- Protool Part Number
- 685-21-3
- Brand
- Asimeto
- Category
- Gauge
Need cutting data? Call 01732 887334 or email sales@protool-ltd.co.uk.
Delivery
Free UK mainland delivery on orders over £50 ex VAT. In-stock items ordered before 4:30pm are dispatched the same working day. Full delivery information.
Returns
14-day returns on unused stock items in original packaging. Special-order and bespoke tooling is non-returnable. Read our returns policy.
Technical Support
Over 30 years of machining experience behind the counter. Call 01732 887334, Mon–Thurs 8:30–17:30, Fri 8:30–16:30.
Trade Accounts
Credit accounts, contract pricing and scheduled call-off orders available for trade customers. Apply for an account.
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.
Full Range: Asimeto Ring Gauges - GO - Metric Fine 6g - 685 Series
View full collection →You are viewing 685-21-3. Click any other SKU to view its full details.
| Product SKU | Size | Pitch | Price | Stock | Order |
|---|---|---|---|---|---|
| 685-02-0 | M2 | 0.35 | £57.92 | In Stock | |
| 685-02-8 | M2.2 | 0.35 | £57.92 | In Stock | |
| 685-02-9 | M2.5 | 0.35 | £57.92 | In Stock | |
| 685-03-0 | M3 | 0.35 | £57.92 | In Stock | |
| 685-03-9 | M3.5 | 0.35 | £57.92 | In Stock | |
| 685-04-0 | M4 | 0.35 | £57.92 | In Stock | |
| 685-04-9 | M4.5 | 0.35 | £57.92 | In Stock | |
| 685-05-0 | M5 | 0.35 | £57.92 | In Stock | |
| 685-06-0 | M6 | 0.35 | £57.92 | In Stock | |
| 685-04-1 | M4 | 0.5 | £53.24 | In Stock | |
| 685-05-1 | M5 | 0.5 | £53.24 | In Stock | |
| 685-06-1 | M6 | 0.5 | £53.24 | In Stock | |
| 685-08-1 | M8 | 0.5 | £53.24 | In Stock | |
| 685-10-1 | M10 | 0.5 | £57.92 | In Stock | |
| 685-12-1 | M12 | 0.5 | £64.58 | In Stock | |
| 685-06-2 | M6 | 0.75 | £44.60 | In Stock | |
| 685-07-2 | M7 | 0.75 | £44.60 | 4 weeks | |
| 685-08-2 | M8 | 0.75 | £49.68 | In Stock | |
| 685-10-2 | M10 | 0.75 | £53.24 | In Stock | |
| 685-12-2 | M12 | 0.75 | £69.66 | In Stock | |
| 685-08-3 | M8 | 1 | £44.60 | 4 weeks | |
| 685-09-3 | M9 | 1 | £44.60 | 4 weeks | |
| 685-10-3 | M10 | 1 | £44.60 | 4 weeks | |
| 685-11-3 | M11 | 1 | £47.75 | In Stock | |
| 685-12-3 | M12 | 1 | £48.51 | 4 weeks | |
| 685-14-3 | M14 | 1 | £64.94 | In Stock | |
| 685-16-3 | M16 | 1 | £58.68 | 4 weeks | |
| 685-18-3 | M18 | 1 | £59.85 | 4 weeks | |
| 685-20-3 | M20 | 1 | £68.49 | 4 weeks | |
| 685-21-3 Viewing | M21 | 1 | £79.83 | 4 weeks | |
| 685-22-3 | M22 | 1 | £72.00 | 4 weeks | |
| 685-23-3 | M23 | 1 | £87.26 | 4 weeks | |
| 685-24-3 | M24 | 1 | £87.26 | 4 weeks | |
| 685-25-3 | M25 | 1 | £78.66 | 4 weeks | |
| 685-26-3 | M26 | 1 | £87.26 | 4 weeks | |
| 685-27-3 | M27 | 1 | £78.66 | In Stock | |
| 685-28-3 | M28 | 1 | £78.66 | In Stock | |
| 685-30-3 | M30 | 1 | £108.77 | In Stock | |
| 685-32-3 | M32 | 1 | £120.51 | In Stock | |
| 685-33-3 | M33 | 1 | £122.49 | 4 weeks | |
| 685-34-3 | M34 | 1 | £122.49 | In Stock | |
| 685-35-3 | M35 | 1 | £122.49 | In Stock | |
| 685-36-3 | M36 | 1 | £139.68 | 4 weeks | |
| 685-38-3 | M38 | 1 | £139.68 | In Stock | |
| 685-39-3 | M39 | 1 | £126.00 | In Stock | |
| 685-40-3 | M40 | 1 | £126.00 | 4 weeks | |
| 685-42-3 | M42 | 1 | £167.85 | In Stock | |
| 685-45-3 | M45 | 1 | £167.85 | 4 weeks | |
| 685-48-3 | M48 | 1 | £174.51 | In Stock | |
| 685-50-3 | M50 | 1 | £174.51 | In Stock | |
| 685-52-3 | M52 | 1 | £171.77 | 4 weeks | |
| 685-55-3 | M55 | 1 | £181.17 | 4 weeks | |
| 685-56-3 | M56 | 1 | £181.17 | 4 weeks | |
| 685-58-3 | M58 | 1 | £181.17 | 4 weeks | |
| 685-10-4 | M10 | 1.25 | £46.58 | In Stock | |
| 685-12-4 | M12 | 1.25 | £46.58 | 4 weeks | |
| 685-14-4 | M14 | 1.25 | £55.94 | 4 weeks | |
| 685-12-5 | M12 | 1.5 | £48.15 | In Stock | |
| 685-14-5 | M14 | 1.5 | £51.66 | 4 weeks | |
| 685-16-5 | M16 | 1.5 | £56.34 | In Stock | |
| 685-18-5 | M18 | 1.5 | £61.83 | In Stock | |
| 685-20-5 | M20 | 1.5 | £61.83 | In Stock | |
| 685-22-5 | M22 | 1.5 | £63.41 | 4 weeks | |
| 685-24-5 | M24 | 1.5 | £68.85 | 4 weeks | |
| 685-25-5 | M25 | 1.5 | £68.85 | 4 weeks | |
| 685-26-5 | M26 | 1.5 | £73.58 | 4 weeks | |
| 685-27-5 | M27 | 1.5 | £81.41 | 4 weeks | |
| 685-28-5 | M28 | 1.5 | £108.41 | 4 weeks | |
| 685-30-5 | M30 | 1.5 | £97.83 | In Stock | |
| 685-32-5 | M32 | 1.5 | £108.41 | 4 weeks | |
| 685-33-5 | M33 | 1.5 | £110.34 | In Stock | |
| 685-34-5 | M34 | 1.5 | £126.77 | In Stock | |
| 685-35-5 | M35 | 1.5 | £114.26 | 4 weeks | |
| 685-36-5 | M36 | 1.5 | £114.26 | In Stock | |
| 685-38-5 | M38 | 1.5 | £114.26 | In Stock | |
| 685-40-5 | M40 | 1.5 | £135.00 | 4 weeks | |
| 685-42-5 | M42 | 1.5 | £163.58 | In Stock | |
| 685-45-5 | M45 | 1.5 | £163.58 | 4 weeks | |
| 685-48-5 | M48 | 1.5 | £163.58 | In Stock | |
| 685-50-5 | M50 | 1.5 | £185.85 | In Stock | |
| 685-52-5 | M52 | 1.5 | £182.75 | 4 weeks | |
| 685-55-5 | M55 | 1.5 | £182.75 | In Stock | |
| 685-56-5 | M56 | 1.5 | £182.75 | 4 weeks | |
| 685-58-5 | M60 | 1.5 | £182.75 | 4 weeks | |
| 685-60-5 | M60 | 1.5 | £214.07 | 4 weeks | |
| 685-18-6 | M18 | 2 | £73.94 | 4 weeks | |
| 685-20-6 | M20 | 2 | £73.94 | 4 weeks | |
| 685-22-6 | M22 | 2 | £79.83 | 4 weeks | |
| 685-24-6 | M24 | 2 | £72.00 | 4 weeks | |
| 685-26-6 | M26 | 2 | £85.68 | In Stock | |
| 685-27-6 | M27 | 2 | £77.49 | 4 weeks | |
| 685-28-6 | M28 | 2 | £85.68 | 4 weeks | |
| 685-30-6 | M30 | 2 | £83.34 | 4 weeks | |
| 685-32-6 | M32 | 2 | £83.34 | 4 weeks | |
| 685-33-6 | M33 | 2 | £85.32 | 4 weeks | |
| 685-34-6 | M34 | 2 | £112.68 | In Stock | |
| 685-35-6 | M35 | 2 | £101.75 | In Stock | |
| 685-36-6 | M36 | 2 | £101.75 | 4 weeks | |
| 685-38-6 | M38 | 2 | £112.68 | In Stock | |
| 685-39-6 | M39 | 2 | £112.68 | 4 weeks | |
| 685-40-6 | M40 | 2 | £163.17 | In Stock | |
| 685-42-6 | M42 | 2 | £163.58 | 4 weeks | |
| 685-45-6 | M45 | 2 | £163.58 | 4 weeks | |
| 685-48-6 | M48 | 2 | £179.60 | In Stock | |
| 685-50-6 | M50 | 2 | £179.60 | In Stock | |
| 685-52-6 | M52 | 2 | £176.49 | 4 weeks | |
| 685-55-6 | M55 | 2 | £176.49 | 4 weeks | |
| 685-56-6 | M56 | 2 | £176.49 | In Stock | |
| 685-58-6 | M58 | 2 | £176.49 | 4 weeks | |
| 685-60-6 | M60 | 2 | £183.15 | In Stock | |
| 685-30-7 | M30 | 3 | £95.09 | In Stock | |
| 685-33-7 | M33 | 3 | £97.43 | In Stock | |
| 685-36-7 | M36 | 3 | £104.09 | 4 weeks | |
| 685-39-7 | M39 | 3 | £104.09 | In Stock | |
| 685-40-7 | M40 | 3 | £160.43 | In Stock | |
| 685-42-7 | M42 | 3 | £160.43 | In Stock | |
| 685-45-7 | M45 | 3 | £160.43 | In Stock | |
| 685-48-7 | M48 | 3 | £160.43 | In Stock | |
| 685-50-7 | M50 | 3 | £160.43 | In Stock | |
| 685-52-7 | M52 | 3 | £157.32 | 4 weeks | |
| 685-55-7 | M55 | 3 | £186.26 | 4 weeks | |
| 685-56-7 | M56 | 3 | £185.49 | In Stock | |
| 685-58-7 | M58 | 3 | £186.26 | 4 weeks | |
| 685-60-7 | M60 | 3 | £198.77 | 4 weeks |
No products match your filters.



