Universal Joints, 1 in (female square); 1 in (male square) drive, 4 1/2 in

Designed for superior performance with ball & socket construction allowing freer rotational movement. Oiled black oxide finish. Forged and machined for best fit and unyielding strength. Precision heat-treated and tempered for optimal hardness, ductility and durability. Easy to read stamp pattern in order to quickly determine opening size.