The following filter cartridges are compatible with the Base Camp Pro/Gravity Camp water filters:
Ultra Flow Replacement Cartridge (art #8019168)
Upgrade Kit (for Katadyn Camp/Base Camp Filter) (art #8019246)—this will turn your existing Base Camp (art #8010655) or Camp (art #8013637) into the new Gravity Camp System
Hiker Pro Replacement Cartridge (art #8014644)—this requires a Base Camp retaining ring to adapt your new gravity system to the older-style Base Camp
Siphon Element (art #1120070)—this will give you a long-lasting ceramic option for your gravity system.