Extremely airtight! The Butyl rubber compound prevents pressure loss and fewer occassions to inflate. Extremely reliable! Quality control for safer cycling: Each tube is checked twice at the factory to ensure safer cycling. Having the correct pressure means fewer punctures and reduced rolling resistance.

20 x 1 3/8" (37-438)500 x 28A (28-440)500 x 35A (37-440)20 x 1 1/8" (28-451)20 x 1 3/8" (37-451)