The Unger Rinse 'n' Go uses the same technology that professional car washes use for spotless and streak-free results. The replacement filter is quick and easy to install. With the Rinse 'n' Go Replacement Resin Filter you can keep getting spot-free results with no need to hand dry. It creates pure water through a process called de-ionization allowing you car to dry without spots or streaks. Resin Filter lasts up to 11 washes. For use with the Unger Professional Rinse 'n' Go Car Wash System (sold separately).