The forward compartment houses a shortened version of Mark S flare. The center compartment provides clearance for the fuze pocket and the rear compartment houses two Type 1 Mark S flares. When charge is passed to fuze, predetermined delay starts running out. Fuze then fires initiating burster charge within gaine. Explosion forces anvil from the fuze pocket, shearing the shear wire and causing container to hinge open.
Static cords connect each flare fuze to the container.
When flare falls away, flare fuze is thus initiated.