The give you the option of adding a gentle gag action is you want it/things go sideways.
So pulling straight back, you just get the french link snaffle as it is. The "wings" on the Stuebben on is about making sure you can't pinch any lips.
The metal is about creating salivation and softness.
Anywho,pull a little harder or life up, and you can draw the bit into the corn ers of the mouth and perhaps produce a little poll pressure.
Unlike a true gag or an elevator it, you can't do anything drastic with these.
Not sure I'd pay $90 to own one. They don't do enough to make me want to buy one of these as opposed to, say, a copper mouth elevator bit that I could do more elaborate things with if I wished.