Available in a Stationary, Single Sheave Unit or a Revolving unit with Single or Double Sheaves. Sizes for shafts with a top diameter of up to 3-1/2" attached via 3 stainless steel set screws. Larger sizes are attached via 3 stainless steel bolts. Contact Customer Service regarding special applications or for stationary truck assemblies for shafts with a top outside diameter larger than 5-1/2".