Most amateur rockets use pyrotechnically pressurized tubes to eject the recovery systems from the vehicle. Common pyrotechnic compositions require pressure to propagate their flame. At high altitudes this pressure is no longer provided by atmospheric pressure, therefore alternative methods are required. One method developed by the team is a cold gas release system.
As part of Project Virgo
We did a lot of this. Prior to ground testing this device was fired 12 times to characterize it's actuation and assembly.
This device flew on Virgo Flight 1 and Virgo Flight 2 successfully deploying a streamer both times. Virgo Flight 2 qualified this device at attitudes >30,000ft.