The wrench is used for unscrewing and tightening of front chain ring nuts the tightening starts with the broader part and when the nut is sufficiently tightened it finishes with the narrower part which is bent in order to enable more secure power transfer during the final tightening of the nut when unscrewing the nut the key is used in the reverse order material special tool steel hardened and tempered surface finish chrome plated according to en12540 the dimension of the hexagonal key