Manufacturer: ‎RUTU. The tough rubber stem seat is also tear resistant to extend the service life of the valve. Better Performance:Butyl Rubber Better Shock Absorption Butyl adds to more stretch, shock absorption, impact and puncture resistance for a smoother ride.Our butyl rubber inner tubes are softer than ordinary rubber inner tubes of competitors.At 2 mm in thickness, these inner tubes are 0.5 mm thicker than average inner tubes in the market.