The NA-73 Mustang I was a sleek, low-wing cantilever monoplane of all metal construction that was designed specifically to meet a British Air Purchasing Commission request in April 1940 for a new fighter to help the beleaguered Royal Air Force (R.A.F.).  Multiple 300 aircraft orders were placed and the NA-73X prototype was ready for air testing just 117 days later.  Deliveries of the Allison V-1710-F3R powered Mustang I to the R.A.F. began in August 1941.  The Mustang I had four cowl mounted 12.7 mm Browning machine guns and four wing mounted 7.69 mounted machine guns.  The first two R.A.F. units armed with the new Mustang Is were No. 2 and No. 26 Squadrons.  A later variant, the Mustang IA was similar to the Mustang I but carried four 20 mm cannons in the wing instead of the previous four 7.69 mm Browning machine guns.  While the R.A.F. oredered 150 Mustang IAs only 93 were delivered before the remaining production was diverted for United States Army Air Corps use.  The Mustang I had the following operational characteristics: 1) Top speed of just under 330 m.p.h.; 2) Combat range of 625 miles and 3) Service ceiling of just under 31,000 feet.  This older NA-73 Mustang I model is molded in light gray plastic and includes the following features: 1) Authentic Mustang I markings for both the R.A.F. and the United Sates Army Air Corps; 2) Clear plastic canopy; 3) Option to create 20 mm cannon armed Mustang IA variant; 4) Recessed panel lines; 5) Separate rudder; 6) Painting guide and 7) Illustrated assembly instructions.  The box is in very good condition but does have a small tape tear on the back and side of package.  Never started and 100% complete with all parts, decals and instructions inventoried.