No. 24 Image Shown R172323 1/4 In Check Valve (Optional) Used on Rainbow Pentair Chemical Feeders Chlorinator Parts Rainbow's 300 series of Off-line pool chlorinators are used when permanent installation is not desired or when there is no room to install the In-line version (approx. 4" of pipe needed to install the 320 In-Line series). The 300 offline chlorinator can be secured into the floor for safety and stability. Includes lid lubricant, 6 ft of hose with two injector fittings; (one hose brings water to the chlorinator, the other delivers the chlorinated water into the return line - past any pool heater). Use only Trichlor or Bromine tablets and sticks.