Rainbow™ feeders not only save time but also reduce manual handling of chemicals. They use large or small trichlor or bromine slow-dissolving tablets to make sanitizing your new or existing pool or spa easy and automatic. Both install easily on the pressure side of the pump, downstream of the filter and heater. The in-line Model 320 feeder both feature an external fine-control valve that lets you adjust the feed rate to meet specific pool or spa requirements. The Model 320 feeder is designed for permanent installation in the return line of new or existing systems and dispenses sanitizer directly into your pool or spa, downstream of all equipment. The feeder extensions increase tablet or stick capacity, so you can vacation without worrying about running out of chlorine