Breakthrough Nylon AR .223 Cal/5.56mm Chamber Brush - This brush fits AR15 .223 / 5.56 chambers perfectly 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 .07lbs 3in x 5in x .5in