Straight rubber mouth pelham. Stainless steel bits can have quite a bitter taste to them which some horses dont particularly like. Rubber Mouthpieces are a warmer feel to the horses mouth, those horses that do not accept stainless steel very well sometime accept rubber very well. The rubber mouthpiece is particularly useful for horses with sensitive bars and/or tongues. The rubber mouthpiece is a milder alternative that stainless steel as the mouthpiece is normally thicker; therefore the pressure is distributed over a larger area. The rubber bits may be unsuitable if your horse is a larger breed which has thicker fleshy lips and/or a large tongue.