The Pentair Union Kit 351157 is designed to connect two pieces of 1-1/2" or 2" plumbing together. It comes with (2) adapters, (2) nuts and (2) O-ring adapters so that it can be installed quickly and easily. This kit is designed for pump applications where the first plumbing connection is 1-1/2" or 2" female buttress thread (fbt), slip (s) or spigot (spg). The second plumbing connection can be either 1-1/2" female buttress thread (fbt) or slip (s). This kit is perfect for those who need a durable, dependable union fitting for their pump.