I cannot speak for the GYRO JET PEN (never heard of it), but I can speak on the TRU-FLARE kits, as i own a couple. They are easy to use, well made, and they simply work. The flares dont go that high though maybe 60- 70 feet. (i'm used to Very Pistol flares, that have much higher altitudes)
I carry one, the flares are replaced with bear control bangers. Simple, easy to use:
prior to "loading" (remove the grey thread cap from the base of the flare or bear banger, and thread the flare/banger into the pen launcher. MAKE SURE firing lever is int he safety detent, or the flare will go off in your hands)
loaded (note firing lever is in the safety detent, its bets to keep your thumb titghtly pressed against it at this stage, to prevent accidental firing)
ready to fire, firing lever is pulled out of the detent and all the way back, (device is held away from the body with one hand and fired with the other)