A circular cylindrical striker member 2 for a drilling machine adapted to transfer kinetic energy to an impulse receiving member 4. The striker member has a diameter d max , and includes a side surface 12 and an impulse surface (6). The striker member is adapted to transfer the kinetic energy to the impulse receiving member by a ring shaped active surface of the impulse surface, wherein the ring shaped active surface is concentric with regard to the cross section of the striker member, has a diameter d a , where d a max , and has a width w a that during the contact moment with the impulse receiving part is less than 0.2d max.