Set of 4 poly wheel casters, zinc plated, rated 300 lbs each. Fits large uprights and most studios with toeblocks - WILL NOT FIT SPINETS OR CONSOLES. Mounting sockets, illustrated instructions, screws, bushings and full Ragland Piano ProFit shim kit included. Instructions and tech support contact info included with shipment. 2" diameter wheel, 1 5/8" wide. Mounting socket is 2 1/8" in diameter with a stem that is about 1.5" tall. Distance from the bottom of the wheel to the top of the socket mounting flange (when socket and caster are together) is about 2 7/8". This kit is designed to be better for wood floors than metal wheels and able to support more weight (300 lbs per caster) than the typical double rubber wheeled caster (160 lbs).