I bought myself 3 of these for a intended 3 stage mid-powered rocket build. I ended up going with two, but it was well worth it. I sat down and read the instructions, they were very clear. I was also happy to find that the kit came with centering rings for a standard BT-55 (or 50, forgot for the time being) and a BT-80 body tube. I used a BT-60. The rings were easy to cut out with a standard hobby knife. The kit also came with a standard Estes engine hook for E size motors, and a D hook, if you only want to fly your rocket with a D motor. This is really not needed, for the kit comes with a D motor spacer. It is orange, and fits into the tube and makes your D motor the size of an E motor. Its a really nice feature for the kit. The whole kit was really easy to put together, and fit nicely into my tubes. My only concern is that you really must glue your hook down. I found that on my first stage, which I threw and E12-0 in, that the hook moved up past the ring. It was secure enough to keep the motor in place, but ripped off the top of the motor mount tube. Overall, these motor mounts are really secure if you follow the nice instructions. They can take the beating of the higher end of Estes BP motors, and look nice in your rocket.

This is just what i needed to fix an error I made building one model rocket. Came just as described.

It is a pain to install in your rocket, but it seems to work well, for me.