Shires Double Jointed Sweet Iron Pelham BitPelhams work on the poll, corners, bars, tongue and chin groove. This bit will assist with control. The jointed mouthpiece will lessen the nutcracker action. The copper and sweet iron will encourage the horse to be softer in the mouth. Raised copper ribs help to prevent the horse taking too much of a hold. Mouthpiece thickness: 16mm. Cheek height: 135mm. Sweet iron mouthpieces are designed to oxidize to produce a sweet taste which helps with mouthing.