This rigid plate caster is load-rated up to 440 pounds, and made of zinc-plated steel. The mounting plate is 4 1/8 x 3 3/8 inches, with inside and outside bolt hole spacing of 2 3/8 x 3 1/8 inches, with a 5/16-inch mounting bolt diameter. The wheel is grey, 1 1/2 inches wide and four inches in diameter. Replacement wheels can be ordered under the number WSD4138GG-2G TG.