If you want to connect a smooth pipe of one size to a female socket of a different size, you would use a Slip x Mipt Reducing Male Adapter. This fitting has a larger connection one end and has a smaller connection on the other end. Be careful when ordering because the nomenclature determines which size is the larger size. For example, if you were to order a 3/4 x 1/2 reducing male adapter, the 3/4 side of the fitting would accept the smooth pipe end while the 1/2 size would represent the male threaded end that would be turned into a female 1/2 socket. All of our Schedule 40 fittings are NSF rated 14 & 61, which means they are certified for use with potable (drinking) water. Maximum temperature is 140 degrees F.