These must be installed with an internal expansion machine and can be reused (except expansion rings and possibly the tail gasket). When installing these fittings it is critical that the internal tail gasket is compressed by the expansion ring - or a hose leak or failure will result within several feet from the end of the hose. Short shank couplings listed earlier in this catalogue can be used for temporary field repair (low pressure). The most common fire hose threads in British Columbia are: 1" to 2" NPSH and 2-1/2" BAT (larger sizes must be confirmed but are typically NH - or also known as NST). NH/NST is more popular in the USA. 'Male NPT' will seat on 'female NPSH' threads, but 'female NPT' and 'male NPSH' will not mate. BAT Thread (made in 2-1/2" size only) will not interchange with NPT, NPSH, or NH threads. The 'bowl size' of a fire hose coupling represents the inside diameter of the expansion side (the thicker the hose wall is, the larger the bowl size).