Plastic Knuckles Size Guide
ONE SIZE FITS NOBODY.
NoMetalKnucks products come in actual sizes because hands do too. Choose the profile you want, download the correct printable guide, and check the scale before choosing Small, Medium, Large, or X-Large.
Ergo and Classic share one four-finger guide. Single uses a separate one-finger guide.
Download the printable guides
Print at 100%
Both current PDFs give the same accuracy instructions:
- Print the page at 100% in your printer settings.
- Place a U.S. quarter over the printed quarter image.
- The quarter should not cover the red border.
- If it covers the border, the page scale is wrong and the measurement will be inaccurate.
Do not use “Fit to Page,” shrink the PDF, or enlarge it.
Choose the profile first
Ergo Knuckle 2
Our fuller, contoured four-finger profile. Use the shared Ergo and Classic printable guide.
Classic Knuckle
Our straighter, flatter four-finger profile. Use the shared Ergo and Classic printable guide.
Single Knuck
Our compact one-finger profile. Use the separate Single printable guide—not the four-finger guide.
Current published dimensions
The current dimension chart shows:
| Size | Finger opening | Overall height | Overall width | Thickness |
|---|---|---|---|---|
| Small | 0.823 in / 2.09 cm | 3.949 in / 10.03 cm | 2.293 in / 5.82 cm | 0.592 in / 1.50 cm |
| Medium | 0.917 in / 2.33 cm | 4.388 in / 11.15 cm | 2.425 in / 6.16 cm | 0.647 in / 1.64 cm |
| Large | 1.017 in / 2.58 cm | 4.819 in / 12.24 cm | 2.642 in / 6.71 cm | 0.706 in / 1.79 cm |
| X-Large | 1.119 in / 2.84 cm | 5.258 in / 13.36 cm | 2.852 in / 7.24 cm | 0.766 in / 1.95 cm |
The live chart marks Large as the general recommendation. That does not mean Large fits every hand. The popup recommends sizing up when you are between sizes.

Between sizes?
If your hand falls between sizes, the current product popup recommends sizing up. If the choice is still unclear, contact NoMetalKnucks and include the profile and size you are considering.
Quick reminder
- Choose Ergo, Classic, or Single.
- Download the correct PDF.
- Print at 100%.
- Verify the scale with a U.S. quarter.
- Compare your hand with the guide.
- Size up if you are between sizes.
Two minutes now beats an exchange later.