The Sig P320. Striker Fired Available in .45ACP, .40SW, .357Sig, 9mm, and .380 cal. When purchased in the 40,357,9mm, or .380 cals they are all interchangeable so you change out the trigger assembly with the frames of any of the others in any variation and you are good to go. REALLY nice gun and inexpensive for a SIG @ less than $600. The US Army has just adopted them in the 9mm full size as their replacement to the M9.