Pro-Shot Bore Mop - 100% Cotton Bore mop made with a brass core. They are made of the highest quality construction possible. Mops can be used for quick cleaning and bore lubrication. Mops are especially excellent when using oil for bore lubrication because they create foaming action that helps in the lubrication process. Pro-Shot Exclusive Quick Clean/Mop Design 100% Cotton Thick Fill American #5-40 Threads Made in USA