Why do you think they have such a confusing model number system? Why cant they make it easy like everyone else. like glock 9mm 4 inch model, or glock 9mm sub compact. No they have to have numbers that have no meaning to what the gun is? Thats why most glock owners don't know what they own. "what kind of glock you have?" reply with a shoulder shrug "a 9mm think it's a 17 maybe a 19?"