Anyone have experience with the KAK Brownells uppers?

https://www.brownells.com/gun-parts/rifle-parts/rifle-receivers-parts/5.56x45-nato-complete-upper-receiver/

Looking for a cheap upper that’s a step above PSA quality. It’s going on an Aero M4E1 lower that’s been in the back of my closet since I built it. Just need something cheap that I can use as a training rifle for new shooters.