The BS and BSRT couplings are mainly used in The U.K., Ireland and Arabic countries. Both are asymmetric, which means the BS coupling has both a male and a female component and the BSRT has both male and female threads. The correct assignment must be strictly observed. The BS coupling is available from 1.5” to 2.5” and it is used for pressure delivery operations. These couplings can be connected by plugging them together. The female end has two spring loaded lugs which are pulled outwards to release the male. The BSRT coupling is available from 3” to 5.5” and is used for suction operations. The female and male threads of the BSRT couplings are also known as British Standard Round Threads. Compared to the Storz, Gost and Nor couplings, the BS and BSRT couplings are not sold individually, but in pairs.