This Vitamix original part is used on many models of blenders. The Drive Socket Kit includes the socket, set screw, and a hex key. The Drive Socket should be replaced if it no longer drives the blades correctly in the blender jar. To install this part first remove the Centering Pad. Next, align the damaged Socket to the hole on the housing and insert the hex key. Then, loosen the set screw. Next, pull the old Socket off the motor shaft. Note that the set screw only needs to be snug. Over tightening of the setscrew can cause it to strip and no longer retain the socket on the motor shaft correctly.