This 3.50-4 innertube (inner tube) with bent valve stem is most commonly (though not exclusively) used for smaller 2-stroke machines. Also commonly referred to as (and can be used in most applications indicated by) 3.50-4, 4.00-4, 4.10/3.50-4 and 11x4.00-4. Frequent uses for this style of tire are 33cc, 43cc, 47cc and 49cc air cooled and liquid cooled pocket bikes, mini bikes and other miniaturized powersports products.