Everpure ® Service Plug - A must have for all Owners of the standard Everpure heads such as the QL-2 and QL-3 (does not work on Pro Series head). Install in place of the filter as is and it will stop the water flow to the faucet. Remove the small o-ring and it will allow water to pass to the faucet. Great for sanitizing or servicing your Everpure system.