Nice small older steel roller wheel I beam trolley for hanging a chain hoist on a steel I beam . American made, when that meant something. Could easily hold 2-3 tons. Made by CM MERCURY in Tonawanda New York state. Fits 4 1/2 to 5 inch wide I beam. For use with the typical jib style crane hoist like most machine shops used to have. Extra thick steel wheels with roller bearings. $ 90