Usage Tips: new and Never Used Set of four (4) Machined Wheels/Rollers Compatible with Total Gym Replacement. The diameter of the bearing thru hole is about 5/16 inch. All bearings are included.<br>Fits 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.<br>Our rollers are made from high quality material solid engineering plastic. That means your Gym is going to be back up and running quickly and operating at peak efficiency.<br>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!!!<br>Manufactured and tested to function as well as original OEM Branded Parts but at a better value than the a comperable original equipment manufactuer part. Please rest assured to buy.