Usage Tips:COMPATIBILITY: 2.75/3.00-21 Inner Tube Fits Motorcycle with 21inch Tires, great 80/100-21 Replacement Inner Tube with TR4 Straight Valve Stem: We designed this inner tube to be explosion proof. When and if punctured, it immediately creates an airtight seal to prevent damage, destruction and injury to the riderGREAT PERFORMANCE: The inner tubes are double thick, more . Improved version thicker rubber tubes which are tear-, scratch- and in useEASY TO INSTALL: The replacement inner tire is extremely convenient and simple to install and detach. Please check the position of the valve, and make sure you install them in the right directionSpecification:Feature: InflatableInner tube is made of isobutylene isoprene rubber, natural rubber in air tightness, elastic damping and aging resistance.Suitable for off-road Chinese dirt bikes, pit bikes, trail bikes and other motorcycles.colour: blackMaterial: rubberPackage Contents: 1 x Inner TubeOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.