The IOSSO AR-308 Bolt Carrier Brush 2 Pack (19125) comes with two brushes that are sized to close tolerance for precision cleaning of the AR .308/7.62MM bolt carrier. The brushes are made with a fiber that is cobalt blue which is a stiffer grade of fiber that allows for back and forth action unlike traditional brass and bronze type brushes. The fiber lasts approximately 8 to 10 times longer than other brushes. The brush is wound tighter and has more fiber per inch than any other brush.

Specs:

8/32 Threading