These drivers will not slip, (cam out), when added torque is applied to install or remove screws. The user can securely engage square head screws without damaging driver or screw head. The power-groove style, 1/4-inch hex shank is compatible with most power drills or screw guns. Fully hardened, Malco square head drivers are also color-coded for easy identification; Green = #1 and Red = #2.