Studies related to the proliferation of POSEIDON C3 led to the conclusion that a new ULMS (missile) and the new submarine concept with greater missile carrying capacity would make the ULMS (missile) more cost-effective than POSEIDON proliferation.The ULMS missile studies tended to culminate in either a 2 or 3 stage missile with a 4500 nm range and a weight in the order of 130,000 lb. Since the missile was to be encapsulated and external to the SSBN, it was size limited. This led to a new FBM missile concept approximately 80 in. in diameter and 56 ft in length. The missile was referred to as LRC3 (Long Range C3) and Lockheed's concepts included a new reentry vehicle (Mk 3A). About this time, the ULMS began to be known as the Improved Fleet Ballistic Missile (IFBM) system.