Used a pair while converting my LOC IV to dual deploy. Once the e-bay is wired up, they're very easy to prepare for flight. Connect an e-match to the terminals and position it into the cup, load it with powder, tamp it in with a bit of ejection padding, close it off with a bit of masking tape and you're off to the races. No muss, no fuss.
Canted, non-square centering rings have always bothered me. When building a high-power rocket, they can make it harder to fit the motor mount into the airframe smoothly, as well as make through-the-wall fin mounting a problem. I just used my Center Ring Standoff the first time last night and it made it a breeze to get the centering ring square to the motor mount tube. I'll definitely be getting the rest of the set, soon!
Roy has great communication if there are any questions andlightning fast shipping! This jig is perfect for all projects sizes from low power models to high power cert flights and is robustly constructed to probably out last most of the rockets built with it