The Herm Sprenger Duo D-Ring Snaffle Bit is a reversible bit. When the V-shaped side is down against the tongue, the small port allows more room for the tongue and thus encourages chewing. When the bit is placed with the flat side against the tongue, it becomes a straight-edged bar bit. The material of the mouthpiece is flexible, yet extremely strong, with reinforced steel cable inside. It's food-safe, solvent-free and made without plasticizers. 16mm plastic mouth. Stainless steel D-rings.