New, sealed and unbuilt. The T1 prototype was built in 1927 with a 37mm M1918 main gun and secondary armament of a 0.30cal M1919 Browning machine gun. The armour was 6.4mm to 9.5mm and the vehicle weighed 7.5 tons. Following successful tests of the prototype, four T1E1 were built. It was standardised for production as the Light Tank M1 but this was stopped. The T1 series were never mass produced and were never used in combat.