[b]Mattias Sweet iron Mouthpiece goes with the Otto combination bit. When you order a mouthpiece for your combination bit, please select a size that's 1cm larger. [u]Please understand:[/u] We make the mouthpieces just for you once you order. So, you can't return or exchange them. We create them from our standard loose ring bits to fit your needs[/b]. This lets us give you a variety of mouthpiece options and sizes for your custom bit! Fager Mattias is a good choice for horses who you would describe as the following: * Can be worried in the mouth but get too stiff on straight bits * Reluctant to soften down into the bit. * Requires encouragement to seek out the contact and keep a consistent contact. * Can overreact when you take the reins * Can get on and off in the contact