This COS11 single stack model is a Commander/Mid-Size length (4.25″) carry gun in 10mm. it includes a tactical (rail) steel frame, ambi-safety, flat trigger, square trigger guard and night sights. Weighing in at 32.3 oz. (steel frame), this lightweight carry gun shoots like a much heavier gun due to the modular COS11 design. The advantage of the COS11 and COS21 is that they have less muzzle flip which makes for a more accurate gun.