Yes, this is a bitting up question. Throwing that out right in the beginning so everyone can cringe ahead of time.
Now to the explanation. Cally is a very large, very strong 16.2hh WB mare. In the arena she is very respectful and listens to my body. If I pitch forward she will stop and allow me to rebalance. Sometimes she gets a little strong, but nothing I can't handle or control. This mare has had 10yrs of professional dressage training. When I ride huntseat she's ridden with a running martingale ONLY because she likes to grab the bit & tug on it. She tries it a couple times with the martingale then stops & starts to work like she should. We only started using it because she could easily unseat me just by doing that. Other than that contact is either light or collected (yes by having her push into the contact NOT forced frame). Riding outside though is an entirely different matter. She can be a nervous/flighty horse. I have plans to eventually start XC schooling her, but I want to get her as solid outside as she is in the arena.
This is her regular bit, my trainer was riding her in a loose ring single joint snaffle before: (she has been ridden in a double bridle before)
Cally can easily run through this bit. Yes, I know, a horse can stop listening & run through any bit. I'm looking for a bit that will basically be the emergency back-up brake. Like I said contact to her mouth is very soft. I am NOT a rein yanker. I only plan to use it a handful of times before switching back to her regular bit. It does need to be XC/Eventing legal in case I decide to use it at shows.
Now I did buy her this bit:
And she didn't seem to notice a change. I worked her in the arena first to see how severe it would be & if I even WANTED to use it outside. It didn't bother her. I took very light contact and like I said - she stopped just with my body in the arena. I barely had to touch that bit. We go outside though & she's running through my hands. Perfect inside. Not listening outside. Which yes I know it's a training issue outside. Hence why I'm asking about a bit to use as an emergency brake should I need it so I can work her outside & get her going just as well. Running through my hands just at a walk though is not good.
(the ride outside that day did go fine, but I didn't do anything fast we mostly walked. Which is how we will be starting out for awhile. Like I said this stronger bit is NOT going to be long term & it's only a "just in case" precaution.)