Steel and cast iron caster swivel wheels. These are very heavy duty. These workhorses have been in use for decades and are still extremely strong! Four holes to attach to whatever project your heart desires! As-is, unrefurbished. These are not reproductions in weak modern metal from questionable sources, these are true vintage hardware. Available individually, price per each. Measurements: 3 inch diameter wheel x 1 1/8 inches wide, sits 3 5/8 inches tall.