This is a holder for attaching a pencil to the tubing of a French horn. It may also be attachable to a trumpet, but this has not been confirmed as there is no actual instrument to test it on. Please check the size. Two pieces will be sent as a set. Size: Approximately 2.5 x 1.2 This is a no-brand product. There may be some size variations. If you are looking for perfection, please purchase a branded product. We are not responsible for any problems that may occur during use.