5RV Lyre mouthpiece for Bb clarinet that was designed by Robert Van Doren and provides time proven standard for musicians worldwide. With its medium facing, Profile 88 beak and tip opening of 109+ (1/100mm), it provides an impeccable intonation, crisp and accurate articulation, and unrivalled response. This mouthpiece is slightly more open than the standard 5RV and works best with Vandoren #3 to #4 reeds.