We've flown it a number of times now on a small test booster and sustainer at our local park to make sure it works. The full details of how the mechanism works are here:
http://AirCommandRockets.com/howitworks_2.htm
The results of the test flights are here:
http://AirCommandRockets.com/day63.htm
We are keen to try it on bigger boosters and sustainers, although we will have to fly it at Doonside since the local park is too small. I'm not sure we will get a new booster built by the 26th Launch date, but should have it for the next one.

- George