This page covers M4 Spring Lock Washers to ISO 7980 / DIN 127: the full dimensional row, hole and tool sizes, proof-load data and typical applications. All values are taken from the governing standards (ISO 7980 / DIN 127 together with ISO 273, ISO 724 and ISO 898-1 where applicable).
M4 Dimensional Row (ISO 7980 / DIN 127)
| For bolt size | Inner diameter d1 min (mm) | Outer diameter d2 max (mm) | Width b (mm) | Thickness s (mm) | Reference standard |
|---|---|---|---|---|---|
| M4 | 4.1 | 7.6 | 2.5 | 1.0 | ISO 7980 / DIN 127 |
Spanner & Drive for M4 Spring Lock Washers
Drive geometry for M4 Spring Lock Washers is given by the row above; match the tool to the listed values.
Common Applications for M4 Spring Lock Washers
M4 Spring Lock Washers are commonly specified for small electronics hardware and precision assemblies.
Installation Tips for M4 Spring Lock Washers
- At M4 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.
Mating Parts for M4
A M4 flat washer pairs with a M4 bolt/screw and matching M4 nut.

