fits a glock 27 or 33. you can use this to shoot .40 cal out of your Glock 33 357sig to save on ammo cost. that is what I originally bought it for. I used it for a couple hundred rounds and lost it in the safe. this is a ported barrel. bought it from Glockdoc.com a few years back. barrel is in excellent condition and really hasn't been shot that much. $80 shipped. if you use pay pal add 3%, if you use a check I will wait until it clears before shipping.