Rainbow's 320 series of inline chlorinators are designed for permanent installation in the return line of pools and spas. No need to drill any holes. Comes with standard 2 inch. slip PVC pipe fittings and adapter for 1-1/2 in. slip installation. Works on the pressure side of the pump and is to be used with slow dissolving Trichlor tabs and sticks or bromine tabs and sticks. Includes a heavy-duty 1/2 in. control valve and a replaceable 1/2 in. check valve. Unit comes with feed line installed in the bottom of chlorinator for normal use but is also drilled and tapped at the top of chlorinator if additional chlorine/bromine dispersion is required. Top feed 1/2 in. x 18 in. extension tubing is included.