It will depend on what mouthpiece is chosen as to the action of the bit. You need to choose a Mouthpiece and a Cheek piece.
Is a way of having only one bit in the horses mouth and being able to ride with two reins. Particularly useful in the Showing World.
Traditional Gags are really the Balding the Cheltenham and the Duncan
Bits that are used for controlling carriage driving etc
Double Bridle Bits
The whole point of choosing to use a Double Bridle should be for refinement and definition.
A variety of non-bit products including Stubbs products and textiles.