These are very basic inserts that convert your 20 gauge shell to a 12 gauge shell.
The ejectors kick out the insert as they would a 12 gauge shell but with considerably less force of course since it is a stainless steel tube.
The operation went like this:
1) Break open the action
2) Cover adapter/shell with hand
3) Catch adapter/shell with hand
4) Dump spent shell (there are cans next to the stands at Etowah)
5) Insert adapter
6) Insert 20 gauge shell
The 6 steps may sound like a lot but for me it's really only 1 additional step (insert adapter) as this is how I clear and load on the course anyway.
These are really only for break action guns as a pump or an auto will not cycle the sub-gauge shell. http://www.shotgunadapter.com/