For application use where an in-wall suction vacuum line is used. This replacement Vac Lock safety mechanism is designed with a spring action cover which holds the pool cleaner hose in place and will snap close the suction fitting automatically when not in use. Can be used with all suction pool cleaners such as the Hayward Pool Vac, Navigator, Baracuda, Kreepy Krauly and many other suction pool cleaners. To install, simply thread the vac lock into pools dedicated suction wall line and secure with set screw ( included). The suction wall fitting will be a 1-1/2" female threaded fitting located on the pool wall. Connect the end of pool cleaners vacuum hose line into the Vac-lock as shown in the photo above. Note: not all pools will have a inline suction wall fitting, so please check your pools plumbing prior to purchasing this product.