 It is difficult, therefore, to compare a harsher-type bit with a mild mouthpiece (such as a pelham with a rubber mullen mouth), and a milder-type bit with a harsher mouthpiece (like a snaffle with a slow twist).In general, however, the mouthpiece can have a marked difference on the severity.Snaffles with twisted wires are never considered mild, while a pelham with a low port may.