"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 Brand MOOSE RACING Vendor Part Number M20078 Duty Standard Inner Tube Valve Stem Type TR-4 (Round Base), Center Metal Valve (Threaded/Nuts) Material Butyl Polymer Mounting Position Front/Rear Product Name Inner Tube Rim Diameter 21" Tube Fits Tire Size 2.75-21, 3.00-21, 80/100-21, 90/100-21, 90/90-21, 100/80-21 Type Motorcycle Units Each