The Herm Sprenger Duo 3-Ring Bit has a 16 mm mouth made of soft, flexible plastic. Designed to be gentle on the horse’s mouth, the Duo can be used two ways depending on the way it is attached to a bridle: straight bar or a bar with space for the tongue.  The leverage effect can be modified through different rein attachment options on the rings. The mouthpiece is food-safe, solvent-free and contains no plasticisers. It is reinforced with a steel cable core. Stainless steel rings are 70 mm.