Treadmill Doctor Belt for Proform 520 ZN, Model Number PFTL591120 DURABLE CONSTRUCTION: The Treadmill Doctor treadmill walking belt are made to last. Engineered with 2-ply commercial quality, Treadmill Doctor walking belts are perfect for both commercial and residential treadmills. These may also be called running belts, treadmill bands, striding belts, jogging belts, etc. FLEXIBLE: Treadmill Doctor walking belts are more pliable than other manufacturers walking belts. Stiffer walking belts make it harder for the belt to rotate on the treadmill. This extra strain on the motor will lead to quicker part failure. POLYESTER-BLENDED BACKING: The backing on the belt is the most important area. Our polyester blended backing gives you heat resistance, quieter operation and a material that will withstand significantly longer than walking belts used by other sellers. PRE-LUBRICATED: The treadmill walking belt by Treadmill Doctor has been pre-lubricated and includes an additional application of lube. It is recommended to lubricate your walking belt at least once a year to reduce friction and stress on the other components of your treadmill. INDUSTRYS LONGEST WARRANTY: The Treadmill Doctor treadmill walking belts come with a one year warranty that covers defects in materials and workmanship  the industrys longest warranty. Some models even offer longer warranties!