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