Mr. Heater Fuel Filter - This in-line filter hooks to the adapter hose while connecting your Buddy Heater to a bulk propane tank. Adds life to your heater by filtering out the particles flowing from your propane tank to your heater eliminating clogs. For use with Mr. Heater Big Buddy and Tough Buddy heatersBlocks small particles in your bulk tankfrom clogging up your fuel lines in the heaterExtends the life of your heater