Breakthrough Nylon AR10 .308/7.62 Chamber Brush - This brush fits AR10 .308 chambers for precision cleaning. Stiff Nylon Bristles Easily Attack Heavy Fouling Nylon Bristles Will Not Flatten Or Damage The Bore Rugged Brass Core #8/32 Thread For Attachment To Breakthrough Clean Stainless Steel Rods .05lbs 4in x .25in x .25in