I cannot recall who made this upper. It is a side charging upper for a MAC 10/45 that I had for my Powder Springs gun a few years ago. The barrel is threaded for a matching suppressor for the original MAC 10. The sights are HK sights (like on an MP5) and it has a rail for mounting optics. All the parts are included to mount the CAR stock to the gun. There are a few parts thrown in. It does not slow the rate of the gun. I liked the fast rate. Lean into it and fire 3-4 shot bursts. Before the gun lifts up you have 3-4 shots on target. The gun was unique for it's fast rate with 45ACP! LAGE makes a similar upper and along with other accessories but you will be paying over $1200. I notice it is out of stock now. I will sell this for $600 shipped and insured. My email is: firstname.lastname@example.org (remove spam) and I will need an official check.