We have Watts WQCFU-T-11 3 Stage Kwik Change Ultrafiltration Replacement Filters. This is a yearly filter pack and it includes:

2 – WQCSC11 11″ Sediment PreFilter (Red)
2 – WQCCC11 11″ Carbon Block Prefilter (yellow)
1 – WQCHFC11 11″ Hollow Fiber Ultrafiltration Membrane (Purple)

The Sediment Filter and Carbon filter needs to be changed every 6 months while the membrane needs to be replaced annually. Everything you need to keep your system working optimally for a full year.

Twist to remove.