Detachable shelf instantly converts rock-n-roller into long shelf (50”x16”) or short shelf (32”x16”) cart. Breaks down into 2 pieces for storage. Tough powder-coated steel tube with carpet-covered 1/2” ply. Kit includes shelf, support tubes, and 4 wing bolts. Load capacity 150 lbs. Weight is 10 lbs. Fits models R8, R10, R12. Fits models with pre-drilled handles only.