A precision machined, silver plated brass ring that fits around the receiver of Bach and Getzen trumpets.
The Reeves Receiver Ring improves slotting and projection, centers the tone and strengthens the harmonics. This results in better projection and a stabilized upper register.
The receiver ring  prevents the dissipation of energy that often occurs at the interface of the mouthpiece and the receiver. Many players use it all the time, while some use it for lead playing, then slide it off for a less intense sound for playing solos.