does the unit sit on the table with the gun.or is it like the chrony and a stray bullet will take it out,thanks,keith

The wires which connect the unit to the screens are about 20 feet long, so you can set it anywhere convenient.

The third skyscreen (proof channel) is a "belt and suspenders" approach. The Oehler is so dependable that you'll know if an abberation occurs without using the proof channel. It's not very expensive, but I simply don't feel the need for it.