If you would describe your horse as something with the following;
Pulls/lean on the bit. Strong.
Making sudden fast head-movements to escape the connection from the reins.
Try to put the tongue over the bit.
Dislike almost every bit you have tried
Julia's double-jointed mouthpiece creates space for the tongue and therefore relieves it from constant pressure.
The Roller reaches further down than the joints. This increases the point-pressure on the tongue if your horse pulls or being heavy in your hand, not consistently.
It also gives the horse something to play with, which is great for horses that can feel numb to the contact.
Together with the taste of sweet iron and copper, this bit is accepted even by very picky and sensitive horses. It increases acceptance and steady contact.