This rigid plate caster is load-rated up to 500 pounds. Made of steel with a zinc finish, the mounting plate is 4 1/8 x 3 1/8 inches, with a 5/16-inch mounting bolt diameter, and inside and outside bolt hole spacing of 2 3/8 x 3 1/8 inches. The wheel is 1 1/2 inches wide and four inches in diameter, with a silver steel core and cast iron tread. Replacement wheels can be ordered using the number WCS415B.