We have Watts WQTSC-10 QT Quick Twist Sediment Prefilter. The is the replacement filter used in the Watts WQT4RO11-50 Quick Twist RO System. Changing the WQTSC-10 requires no tools making filter changes quicker and easier than ever. We also have the Watts QT membrane and a Watts QT filter pack so you can change your entire filter system together. It's an excellent, affordable way to keep your reverse osmosis system running clean.