Treadmill Doctor Healthrider S300i Treadmill Running Belt Model 299301 Review HelpfulOwl Treadmill Belts June 12, 2018September 2, 2018Exercise & Fitness, Exercise Machine Parts & Accessories, Sports & Fitness, Sports & Outdoors, Treadmill Doctor 0 Comment This is the replacement walking belt for the Healthrider S300i Model 299301 Walking Belt Size 19×112