The Bob Reeves Sleeves for Trumpet Mouthpieces are designed to be used with Reeves trumpet mouthpieces that have been cut for sleeves. Used for regulating the gap between the end of the mouthpiece and beginning of the leadpipe inside the mouthpiece receiver. Size number 1 is greatest gap, 6 is the smallest. The Bob Reeves Sleeves for Trumpet Mouthpieces are available in silver finish.