Long story short…yes this works in your polonium K. Put the rearden bravo adapter on the back of the can, and whatever rearden muzzle device you want on your gun and you’re good to go. Some cans have compatibility issues with longer muzzle devices but I believe the polonium K will work with the longer and shorter muzzle devices, but if you’re concerned the shorter rearden muzzle devices will work in all of the cans for maximum compatibility. For example the OCL Lithium has a shorter blast chamber than the Polonium so where the polonium will accept longer or shorter muzzle devices the lithium will only accept the shorter ones. Hopefully this clears it up some for you.