This is a replacement Treadmill Doctor Pulley Drive Belt, model numbers 0K63-01066-0001 or GK63-00002-0079. It is an OEM part, not aftermarket, and is compatible with various Life Fitness models including 90R, 95R, 95Re, 95Ri, 95RW, 95RWEZ, C3, C7i, C9i, LC-5500, LC-6000, LC-6500, LC-6500HR, LC-6500N, LC-8500, LC-9100, LC-9100T, and LC-9500. The belt is designed for use in Lifecycle upright and recumbent bikes, ensuring optimal performance and durability.