This bit allows mild leverage and helps with control. The sweet iron and copper mouthpiece aids salivation and acceptance of the bit. The ring is larger on the 5" & 5.5" so the bit remains in proportion with the larger horses head. Raised copper ribs encourage salivation making this bit ideal for dry mouthed horses.
Stainless steel is the most common material for bits. Durable, easy to clean, tasteless and it does not rust.
Sweet iron mouthpieces are designed to oxidize to produce a sweet taste which helps with mouthing. Copper ribs and inserts will encourage mouthing but also ensure the horse will not take up too much of a contact, ideal for horses that can take a hold.