Punctures are a memory. The SmartGuard layer made from a flexible, special rubber offers particular resistance to shards of glass and flints. Even a thumbtack cannot penetrate this protective layer. The SmartGuard belt does not increase rolling resistance. The MARATHON PLUS rolls as easily as a tire without protection.   Features Size: ETRTO 40-584 (27.5 x 1.50 Inch). Type:Wired. Compound:Endurance. Execution:SmartGuard. Color:Black-Reflex. Skin:Twin. Weight:920 g (32 oz). Pressure:4.00 - 6.50 Bar (55 - 95 psi). Maximum load:100 kg.