I had the old Pur Hiker and bought this replacement cartridge. I was able to screw the top off and replace it with the new cartridge. It comes with a thin layer of plastic to wrap around the cartridge for more protection. The lub helps slid on the tube. I pumped some fresh water and its working. Instead of buying a brand new water petrification kit this replaced a perfectly fine working item but now its brand new because the cartridge is fresh.