: One famous example involved the AutoKeyCard , a metal card engraved with the design for a lightning link (a type of auto sear). Despite being sold as a novelty, federal agents argued that the design was intended for conversion into a machine gun.
A “drop in” auto sear is designed to convert a standard semi-automatic firearm into a fully automatic one with minimal gunsmithing—often just by replacing the rear trigger housing pin. In the world of AR-15s, a device like the “Auto Sear” (often called a DIAS for Drop In Auto Sear) is a small, engineered block that fits inside the lower receiver. Drop In Auto Sear Keychain