Breechtool Tactical Ops PackBreechtool Tactical Ops Pack contains a black Original Breechtool, 5 green brush heads and 5 black brush heads specifically designed to clean the hard to reach areas of your weapon system. The green brush heads are made from . 35mm nylon 610 that has an adherent quality to pick up and dislodge debris. The black brush heads are firmer, with . 45mm nylon 610 and are more effective on stubborn dirt. Nylon 610 has excellent chemical and wear resistance.