picked up a cat m4 bolt tool today very handy for getting that bolt carrier group squeeky clean. gets those hard to reach areas clear of carbon build up. the end opposite of the pronged end is used to clean the inside on the bolt carrier of carbon. it has a slot for holding a large patch but i found it worked better just wrapping the red cotton shop towel i use around it and cleaning out the carrier. the other end is used to clean the base of the bolt. it has a groove the bolt sits in and a few turns dislodges all the baked on carbon. the cut out in the center is used to clean the carbon off the base of the firing pin. these areas have always been a pain trying to use various implents like knives screwdriver blades or just plain prolonged soaks to little success. finally decided to try out on of these gadgets and its my new favorite AR15 tool!!!