Inner Tube - Standard - 21" - TR-4 - Center Metal Valve
"Real butyl tubes" made from 100% butyl polymer, unlike other "butyl" tubes, which are blended with 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 tube minimizes natural air leakage while maintaining air pressure for a longer period of time