All the Pratt Hobbies Ejection Canisters use a filament-based ignition system. Basically, it is a very tiny wire that heats up quickly like an igniter. But instead of igniting the pyrogen on a typical igniter, it ignites the black-powder that you place into the canister. This is just as reliable as an electric match or squib, and there is no requirement for special licensing, storage or HAZMAT shipping. These ejection canister-igniters have been tested with all common electronic altimeters.
Ejection Canisters are supplied with 10 inch long wire leads, which are stripped and tinned. Each Ejection Canister is tested for resistance while it is being assembled, and the measured resistance is written on the canister. You can and should use a multimeter to measure the resistance of the Canister before use; if it varies more than 10 ohms, it can be returned to the manufacturer for a free replacement.
We recommend FFFG-size black powder, the same that is used in Aerotech reload kits. Smokeless powder (Pyrodex) works well if the canister is wrapped with PVC tape after loading to improve containment. Always test on the ground to make sure your ejection system works.
The larger Variable Capacity Ejection Canisters are for rockets with more volume to pressurize than can be done by the two smaller canisters. The sliding plug allows you to use an appropriate volume of black powder, and keeps it in contact with the igniter element.