The Air Supply tube is specifically designed to fit modern BMX tires with a strong emphasis on quality. FEATURES: Specifically sized to fit modern BMX tires SPECS: Labeled Size: 20 x 2.1 - 2.45 ISO Width (mm): 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ISO Diameter: 406 / 20" BMX Shaft Type: Smooth Valve: Standard Schrader Valve Core: Fixed Tube Compound: Butyl