For starters! I have been waiting for Junkiez to release this kit after they bought out Bingo for years!!! That being said, I ordered the Mac 10 and this PolarStar kit. I am a tech at Battalion Airsoft Arena in Jacksonville, I am more than willing to do more of these installs but a few warnings. My biggest gripe is that the PolarStar’s “trigger pull” is when the mock fuse and motor connector both recieve power and does not mess at all with the trigger assembly to make the pull any better. I created a custom trigger board and I now use a different trigger mechanism along with shining the play for a nice short, light and snappy trigger pull. Also, the installation guide makes it seem harder than it is, he installs the engine after everything else and it is nearly impossible to get in but if you install it first it goes in very easy with no risk of damage to the product. My final gripe is that the selector mechanism is terrible and came in pieces broken in the box so I had to make my own. Probably won’t happen to everyone but certainly something to look for. Now for the pros. Without the stock or suppressor you literally have a Polarstar pistol. Also, it’s sweet! The what appears to be resin base for the gearbox has a few imperfections but is well built. I did dremel it down to fit a lot easier and sit just right in the hopup to feed 60 rps. If you run one of these you will get hundreds of looks and people trying to buy it. Great product, could’ve had some more testing before sending out to customers but if you have a lot of tech experience it is worth it!