Inner Tube - Standard - 21" - TR-4 - Center Metal Valve

"Real butyl tubes" made from 100% butyl polymer, unlike other "butyl" tubes, which are blended butyl polymer and natural rubber. Each tube is individually boxed with a full range of sizes and valve stem types clearly marked on each box end. 100% butyl tubes minimize natural air leakage and maintains air pressure for longer period of time. All stems are TR-4 type for valve stem.