Fusion, Pro-Series, Government size, Mainspring Housing internals Kit. Comes with the internal pins, top plunger pin, bottom pin, top retaining pin. All Precision CNC machined from bar stock and heat-treated, with Black Oxide finish. Also, includes standard 23 pound(US Gov Spec) Mainspring. All in one kit package. Will work with most all Government and Commander 1911 mainspring housings and clones.