I purchased 3 of these powder checkers and am impressed by the ease of installation and how well they work.
I am more of a "I can install it much easier if I can see it done" and not so much read about how to install it. So I watched the video on you tube.
They work great on my 9mm and 45ACP but was a bit finicky when I tried to set it up for the .223 Remington/5.56x45 using CFE223 powder. The rod tends to rub on one side of the cartridge brass and sometimes the rod won't go all the way down to the powder. This does result in some false alarms. I also had a heck of a time dialing in the alarm area where the case with the proper amount of powder should not trip the alarm. I did notice that when the rod does go all the way to the top of the powder it sometimes goes past that point and pushes the powder aside. This sometimes results in the alarm tripping as it thinks there is not enough powder in the case. I also think the powder I'm using, (CFE223), may be part of this problem. If they could figure out some way to keep the rod from going deeper into the case due to the rod pushing the powder to the side, that would be great!
All in all this is a great system and certainly worth the money.

Installed on Lee Loadmaster - works great. Loading 9mm w/ Titegroup. Ran many tests - 100% on No-Load and Double Load. But +/- 1.6gr it did not catch - but that's not something I expected it to do. IMHO, way better than Powder Cop or Lock-out Die. All Double Alpha stuff I have so far is great. I would recommend them and this product.

I bought it to mount it on a Dillon xl 650 press used for recharging the 9x21, an interesting tool even if not without a big defect, the plastic pad, it enters very precisely into the case and using very fine powder it remains attached for then fall on the shell plate dirtying everything, now I modified it by smoothing it to reduce its section and to create a camber on the end of the pad, I hope it goes better.

[DAA Reply]: As of Sep 1st 2021, the plunger tip is made out of brass which should solve issue.

Works well, it’s a bit finicky and needs a lot of adjustments to get it right, even then it still beeps on the up stroke sometimes. Definitely gives you a piece of mind knowing I’m not under or over charged.

So much easier to use than the Dillon powder checker and more accurate and less expensive. I use this on my Super 1050 with an AmmoBot drive system. This is an absolute necessity for auto driven presses.

Precise enough to avoid empty/low charge or double charge pistol cartrigdes with fast powders.