Pro-Shot Products Military Style AR15/M16 Chamber Brush Designed for competition shooters to withstand frequent use. Like our bore brushes, the chamber brush is also made to last with a brass core and bronze bristles. .223/5.56 Diameter Chamber Brushes are specifically designed for military style rifles with a stainless steel skirt to aid in chamber cleaning. Standard American # 8-32 thread.Item # 223CH Made in America since 1982, use our products once, become a Pro-Shot fan for life.