The AR-15/M16/308 AR chamber mop is designed for dual-purpose cleaning and lubricating of the chamber and locking lug recesses.
It features a long, skinny portion with individually-tied cotton strands for reaching the chamber, and a short, large-diameter section for the locking lug recesses.
These mops are made from cotton or wool, have 8-32 threads, are approximately 3 inches long, and come in a pack of 12.