Maxxis Welter Weight 700x33-50c Tube 48mm Schrader Valve Removable CoreMaxxis 700x33-50c Welter Weight Tube. Maxxis Welter Weight tubes are the standard in performance inner tubes for racing and training. Welter Weight tubes are 0.8 mm thick for extra duribility. Features a 48mm Schrader Valve with removable core for sealant.4717784040066