The sweet iron copper inlay tom thumb (also sometimes called a sweet iron copper Dr Bristol)is a popular bit amongst show-jumpers, being similar in action to an American gag but without the action of the mouthpiece being raised up in the horses mouth. The shank of the Tom thumb bit gives leverage and encourages the horse to keep his carriage lower as well as providing brakes. The combination of sweet iron and copper makes the bit very palatable and almost all horses will salivate and soften in response to the taste. The loose centre link of the bit is thin with copper layered on it to give a sharper action on the tongue