Bach Commercial Trumpet Mouthpieces Model No. Throat Backbore Depth of Cup Approx. Cup Dia. Rim Shape Description 3MV #27 (.144") #56 Modified V 16.87mm Modified comfort rim with a flatter top Commercial Mouthpiece 3S #27 (.144") #56 Shallow 16.64mm Modified comfort rim with a flatter top Commercial Mouthpiece 5MV (Comm.) #27 (.144") #56 Modified V 16.54mm Modified comfort rim with a flatter top Commercial Mouthpiece 5S #27 (.144") #56 Shallow 16.31mm Modified comfort rim with a flatter top Commercial Mouthpiece 7MV #27 (.144") #56 Modified V 16.23mm Modified comfort rim with a flatter top Commercial Mouthpiece 7S #27 (.144") #56 Shallow 16.00mm Modified comfort rim with a flatter top Commercial Mouthpiece 10 1/2MV #27 (.144") #56 Modified V 15.34mm Modified comfort rim with a flatter top Commercial Mouthpiece 10 1/2S #27 (.144") #56 Shallow 15.11mm Modified comfort rim with a flatter top Commercial Mouthpiece