I'm not convinced they are any better than Fox alarms tbh
Had fox for 20+ years really reliable had no issues with them at all, far from it.
Wanted some new ones with the remote receiver a couple of years ago so got the delks I'd always admired. Yes they seem good, got no real complaints. For me they just seem overly sensitive and I cant see the point in plus and minus settings, just one range high to low would have been better.
They are good, but pretty sure Fox are equal and also have vibration settings and receivers.
Some people go back to Fox after Delks so it's not a one horse race.