Keltec sub 2000 factory M-carbo edition, this model in particular comes with all the ad ons from Mcarbo factory done by them Including all metal interior parts ,muzzle break ,cheek pad ,butt pad and optic mount,to be able to fold when running optic. I had them originally remove the iron sights because I was running a optic but they would be included. This model it's the most expensive one from them I personally ran 100 rds NO hiccups, bought new in 2023 and been saved since I own other carbines as well. This are tanks check reviews.