Treadmill Doctor Walking Belt for the Horizon RST 5.6 Treadmill Review HelpfulOwl Treadmill Belts June 4, 2018September 2, 2018Exercise & Fitness, Exercise Machine Parts & Accessories, Sports & Fitness, Sports & Outdoors, Treadmill Doctor 0 Comment This is the replacement walking belt for the Horizon RST-5.6 Treadmill Model.