The English company making this devise folded, from what I understand.
Basically, it is like one of the gas struts that lifts your hatchback, but in reverse. It pulls open at a specific load. The idea was that in a hard jibe, it would ease the stress on the rig. They made them in three sizes.
The problem is that by the time the spring is stiff enough to hold the windward sailing load at near the reefing point, even the most monstrous accidental jibe will not extended it. It messes with mainsail trimming, without protecting the boat. I tested it on both my F-24 (video below) and the PDQ 32 (it had to be placed inside the tackle on the PDQ to reduce the load).
The best answers remain:
- Control the jibe through careful sheeting. Keep the vang on and bring the sheet in either before the turn or during.
- Keep some stretch in the mainsheet and vang systems. Dyneema does NOT stretch and transmits much larger shock loads. Leave it to the racers who enjoy replacing broken stuff. Use polyester double braid (nylon is too stretchy).
- Keep some stretch in the traveler as well. Polyester is good and nylon is even better (it only gives a few inches, which does not ruin trim--some racers have gone to nylon travelers for smoother crash jibes). Dyneema is a resounding NO.