PF-4501 looks like a Navy version of the basic U.S. Coast Guard National Security Cutter. PF-4921 is the really interesting version IMO.
http://www.defensemedianetwork.com/stor ... ationally/
On the other hand, the PF 4921 is a light frigate for executing anti-air, anti-surface and anti-submarine warfare. However, it sacrifices range – which is about a third less than the PF 4501 – for vastly enhanced combat capabilities. Armament is a 76 mm main gun, a vertical launch unit for the evolved Sea Sparrow Missile (ESSM), a Phalanx or SeaRAM CIWS, and six crew-served as well as remotely operated machine guns. Mounted aft are two quad packed Harpoon surface-to-surface missile launchers and a triple torpedo tube launcher. Sensors shown on the concept ship include a CEAFAR radar system, a hull mounted sonar and a towed array sonar system. Ship’s complement is 141.
No drawings yet but the photos of the models give one an idea of how some of the new systems are arrange on the NSC hull.