The joints use ball mechanisms to provide a fluid motion/rotation. They are connected by mutually engaged hexahedrons, this innovative connection disperses the load across the whole outer circumference of the tool. Allows 50 degrees of rotation on each side, 100 degrees in total. Input Drive Size: 3/8" Drive Shape: Squ 3/8 Sq. Dr. Universal Double Joint 3/8 Square Length 65mm Z-series