This is the Proform 350 Treadmill Running Belt. Model Number: PFTL311051. Part Number: 235821. Fits the following models: HealthRider, 500i - HMTL311050, H120 - HMTL399061, Q400 - HMTL399060, Image, Q400 - IMTL399060, Proform, 350 - PFTL311050, 350 - PFTL311051, 350 - PFTL311052, 350 - PFTL319060, 350 - PFTL319061, 355 - 831.307530, 370e Crosswalk - 831.296230, 370e Crosswalk - 831.296231, 525 X - PFTL432050, 525 X - PFTL432051, Crosswalk 365e - 831.295330, Crosswalk 365e - DTL34951, Crosswalk 370e - 831.306100, Crosswalk 400e - 831.296330, Crosswalk 400e - 831.296331, Crosswalk 420X - PMTL394050, Weslo, Cadence 50SE - WLTL398060.. When it comes to replacement walking belts Treadmill Doctor has been a leader in the fitness industry. Our walking belts are made from quality polypropylene materials, 2 ply construction with the backing made of polyester blended material.