The NORD-LOCK® wedge lock washer pair to DIN 25 201 is a purely mechanically acting machine element that secures the bolted joint by preload force instead of friction and is therefore superior to conventional bolt locking devices When the bolt or nut is tightened, the radial ribs of the NORD-LOCK® lock washers press positively into the mating surface. The pair of washers sits firmly in place and movement is only possible between the wedge surfaces. Even the slightest rotation in the loosening direction increases the preload force due to the wedge effect - the screw thus secures itself. NORD-LOCK® offers reliable screw locking, even under extreme vibrations or dynamic loads. Due to the high hardness of the washers, they can also be used with high-strength screws up to and including strength class 12.9.d(mm): 25,3D(mm): 39Surface: zinc flake coatedT=thickness of the pair(mm): 3.4for ø: M24Size(mm): NL24Contents (PAA): 100.