The package includes 3 piece of trumpet mouthpiece (1x 7C, 1x 5C, 1x3C) and 1 pcs Trumpet Mute Silencer. The kit can meet the requirements of difference occasions and stages of learning of the performer. It would be a good gift chioce for freinds or children.7C, 5C and 3C sizes are from small to large, including outer ring, inner cup, inner diameter and inner tube, which all are from small to large . These size changes are very small, that is difficult to be distinguished by the naked eye.The 7C mouthpiece is suitable for beginners or children with small lips, as the structure of the 7C mouthpiece is relatively small, that it is easy to sound when playing, and the high pitch is easy to pronounce. After a period of exercise, the lip muscles become stronger, then you can consider changing to 5C, then change to 3C3C is a more comfortable size for trumpet players (non-beginners). The 3C mouthpiece cup is relatively shallow, compared with the cup of the larger size, which would improve the reaction speed of the lips and makes the treble brighter.Trumpet Mute Silencer is made of aluminum alloy; Length:135mm;Inlet iameter:18.5mm;Outlet diameter: 61mm. Fit all type trumpets; this aluminum mute has a nice sound and does not distort pitch, you can enjoy your practice with this Trumpet mute and your family members, neighbours and pets will not be disturbed any more.