SharkBite U4008LFA Transition Coupler, 1/2 in, 2 in L | SharkBite polybutylene conversion coupling is the easiest way to transition your polybutylene water line to a different-type of pipe. This fitting has color coordinated collars on each end to help you easily identify which side goes with which pipe. The gray colored collar is intended for use on Polybutylene pipe while the tan colored collar is intended for copper, PEX, CPVC or PE-RT. There is no soldering, clamps, unions or glue required when using SharkBite push-fit fittings. This fitting is not intended to be connected to Polybutylene pipe on both sides of the fitting.