Dutch gag bit?
 

I was just wondering what you guys think of this bit. I don't really know much about it and I have a horse with one, I was told it was because the horse liked it but now I'm having doubts.
She was sold as a novice horse but after a few weeks it soon became apparent that she's not. She spooks at everything and occasionally rears. We were told that she's taken off with the womans husband once and I can feel her trying to do it with me, she's really strong and she tosses her head all the time.
Any information?

Are you working with a trainer? If not, I would strongly suggest it.

I school my eventer 100% of the time in a snaffle, but at hunter paces and mini trials I put him in a dutch gag/elevator with double reins for cross country. I rely primarily on the snaffle but have a second rein on the middle ring (first small one after the snaffle) that I can use as a check when he gets strong.

It sounds like it's more of a training problem here. Are you using this bit with a single rein or double? Which rings?

Some horses go well in one, others not. It's often seen as a 'cure-all' for a strong horse but many dislike the action sufficiently to rear.

As Equiniphile said it depends on bit settings, mouthpiece and hands.