Mitas Motorcycle, Scooter and Moped Tubes are made of a Butyl Compound and Heavy Duty are made from Natural Rubber. Tubes have a thickness varying from 1.2 to 2.0 mm, Ultra heavy duty up to 4 mm. The valve stems on Mitas tube use a fully metal threaded TR4 or JS87 with a Circular base or TR6 Oval base.