External tooth lock washers manufactured according to DIN 6798 allow the immobilization of fasteners such as bolts and screws which are subject to vibrations while maintaining uniform tightening torque in any mechanical electrical or electronic application. In addition to these anti-vibration properties, this washer also improves the quality of electrical circuits as each of the outer teeth forms an excellent point of contact. This washer is recommended for use in inaccessible application zones where it may be difficult to tighten the bolt or screw once fitted. The fact that Form A has teeth on the outer circumference of the washer means that there is uniform contact on the biggest possible surface area, thereby reducing the danger of loosening. The surface of the bolt or screw should be flat and perpendicular to its vertical axis. The permanent inclination of the teeth, which are superimposed one upon the other around the circumference of the washer, gives a very high friction factor allowing for progressive and evenly distributed tightening torque around the head of the bolt or screw. The tightening torque applied on the teeth of this washer should in no case exceed the recommended tightening torque for 8.8 class bolts. When tightening torque is applied, the edges of the teeth of this washer are incrusted in the head of the bolt or screw, forming an immobile unit resistant to loosening.