Total Gym Replacement Set of 4 Wheels/rollers for Models 1000, 1400, 1500, 1600, 1700, 1800, 1900, Achiever, Core, Elite, Force, Gold, Gold Plus, Max, Platinum, Platinum Plus, Power Platinum, Premiere, Pro, Supra, Supreme, Ultima, Ultra, X-Force, and XLi All bearings are included Wheels are designed with smoother and quieter material Lab and gym tested and approved STRONGER, QUIETER, and LAST LONGER than originals and any other aftermarket products!!! Brand New and Never Used set of four (4) Total Gym Replacement Wheels for models Total Gym Replacement Set of 4 Wheels/rollers for Models 1000, 1100, 1400, 1500, 1600, 1700, 1800, 1900, Achiever, Core, Elite, Force, Gold, Gold Plus, Max, Platinum, Platinum Plus, Power Platinum, Premiere, Pro, Supra, Supreme, Ultima, Ultra, X-Force, and XLi. The diameter of the bearing thru hole is about 5/16"