Manufactured in Wyandotte, Michigan prior to the 1986 registry cut-off, and currently not installed in a host firearm. While deceptively simple in construction, being an aluminum block holding a steel trip sear and a small spring, its pre-86 registration status makes it an express ticket to build nearly any configuration or variation of AR-15, M16, M4, etc., including in calibers and patterns not even conceived before 1986. The possibilities are virtually endless.