Stainless SteelAll natural Rubber470241 The EcoPure by Centaur Jointed Full Cheek Bit features mouthpiece material that is friendly to your horse and mother nature. It's made with all-natural rubber with no fillers.Compared to standard rubber mouth bits, EcoPure bits have refined, thinner mouthpieces and better strength and abrasion resistance. These bits are environmentally friendly as they're engineered with materials that pass REACH's strict standards. This EcoPure bit has stainless steel cheeks.