This is a Elftmann Tactical Trigger known as the SE, model ELF-SE-S.
The ELF-SE Drop-In Trigger maintains the Elftmann reputation for quality" craftsmanship and customer service in an affordable package. The mid-weight hammer combined with the exclusive .043 double wound polished piano wire hammer spring provide reliable ignition and fast lock time. Made of wire EDM machined" hardened A2 tool steel and lightweight aircraft-grade aluminum.
Features:
Ultra-Light Housing
Fast Lock Time
3.5lb Pull Weight