provided with an externally threaded portion 32 the diameter of this portion 32 is such that it is able to threadedly engage with the faucet head 13 the anterior end 28 can be further provided with an anterior end nut 33 for tightening the coupling 25 to and loosening it from the faucet head 13 in one embodiment positioned between the nut 33 and the threaded portion 32 is an anterior gasket 34 for sealing the connection between the coupling 25 and the faucet head 13 in an optional embodiment the coupling 25 is further provided with a backflow connector 42 and backflow preventer 43 this backflow preventer 43 can be any of a variety of designs known in the art such as a ball type backflow preventer as illustrated the backflow preventer 43 is a vented or slotted type that allows flow through from the posterior end 29 toward the anterior end 28 but not back in the embodiment illustrated the backflow preventer 43 and backflow connector 42 are slightly smaller in diameter than the anterior internal bore 30 the backflow preventer 43 has a ring portion 44 for mating with the anterior end seat 35 in one aspect the external diameter of the ring portion 44 is of the same or similar diameter as the external diameter of the connector 42 the connector 42 has a threaded portion 45 that is threadedly engageable with the internal anterior threaded end 31 of the coupling 25.