Bore Tech"s Rifle Bore Mops are 100% cotton. These mops can be used to apply solvents or rust preventing agents to teh bore as well as polishing and removing excess solvents from the bore instead of using several patches. Made with the same attention to quality and detail as the Bore Tech brushes and jags.A must have in any shooter"s range box.- Caliber: .40-.45- Threads: 8/32- Length: 2.6