CLENZOIL COBRA BORE CLEANER 20 GA. The Clenzoil Cobra is a high quality bore cleaning system that incorporates all of the essential components of effective bore cleaning into one unique design. When used in conjunction with Clenzoil Field & Range solution, the Clenzoil Cobra provides a quick and easy solution to regular firearm maintenance. Its integrated bronze brush effectively loosens fouling and lead, and the woven cotton braid that follows collects the debris. Completely washable, the Clenzoil Cobra can be reused over and over again.