Dever Tom Thumb Bit with Copper Lozenge.

The Stainless Steel Tom Thumb is a popular bit amongst showjumpers and
eventers. It has a similar action to an American gag but without the
action of the mouthpiece being raised up in the horse’s mouth. The
mouthpiece of this bit is a combination of Stainless Steel & Copper. The
Copper lozenge softens the joint action. The Stainless Steel cheeks give
leverage, with the reins attached to the lower ring. It encourages the
horse to lower its head & also provides brakes.

The Copper makes this bit very palatable and almost all horses will
salivate and soften in response to the taste.