1/2" Drive 4 Piece Flip Impact Socket Set. Sizes 3/4" to 1-1/16", 19mm, 21mm deep. Our impact sockets grip the fastener across a broader contact area, reducing chance of rounding off fasteners. They also allow up to 20% more torque to be applied than on other impact sockets. The shift in pressure allows us to reduce the socket wall thickness, increasing access to tight areas.