Mike Manes devised this gizmo. The idea is that when the lifting force of a balloon suddenly disappears (burst) the "jaws" at the top of this device snap open releasing the ring attached to the upper run of the support line and the remains of the balloon. With the separation of the burst balloon's envelope, the payload train, from the release mechanism down, will not become entangled with the shards of latex. This helps to ensure that the parachute deploys properly and the payloads descend in an orderly manner.
Mike gave a presentation on this device at GPSL 2006. The powerpoint of that presentation is AVAILABLE HERE.
During a recent flight (EOSS133/134) we got back some balloon shards from a Quick Release equipped balloon. See photo and commentary HERE.
Device being held in its operating orientation by Mike Manes, W5VSI. His left arm represents the balloon's lift, his right hand the weight of the payload train. A sudden decrease in lift (a quick lowering of his left arm) will separate the support line in his left hand from the release mechanism and "payload train" in his right hand.
Barometric pressure sensor (anaeroid cell). This sealed cell expands as outside air pressure decreases. As it expands...
This brass colored plate is forced into an unlocked position which effectively activates the release mechanism. As long as the plate is locked, the release will not function. This is a safety feature to ensure that the balloon gets airborne with lots of bounces, travels through the troposphere where the more violent winds are expected before the release is armed.
If you look closely you can see the piston (just to the right of Mike's index finger) that is attached to the pressure sensor. As the anaeroid cell expands during ascent it forces this piston to open the latching device. Mike's finger is simulating the force so that the release is active so that he might demonstrate it at the meeting.