Pratt Hobbies, Inc.
Rocketry Catalog
Model Rocket Kits for Classes and Groups
Launch Systems and Accessories

Variable Capacity Ejection Canisters are for rockets with more volume to pressurize than can be done by the smaller canisters. The sliding plug allows you to use an appropriate volume of black powder, and keeps it in contact with the igniter element. Add the propellant to the Canister and push the foam plug down as far as necessary to hold it against the filament in the bottom.

Each Ejection Canister is tested for continuity before being packaged. Always test on the ground to make sure your ejection system works. Ejection Canisters are supplied with 10 inch long wire leads, which are stripped and tinned.

Detailed information here