Gag bit flexible rubber

Simple rubber: Sweetest bit, gives a lot comfort, ideal for sensitive horses.

Gag bit: Works on the horse's balance forces him to get his own balance. ant putting his weight on his hindquarters. It needs specific cheek parts. If can also be used with only one pair of reins, or with bit loops, or with 2 pairs of reins. 

The right bit is soft. Allows a symmetrical contact, that's why some riders use it as soon as they break in.