This ebonite mouthpiece is very similar to the 5RV so is great for student clarinet players. It is responsive and easy to control in all registers, which makes it perfect for symphonic, and chamber music.
The 5RVL 13 series has a bigger tip opening and longer facing length then the 5RV.
The '13 series' was designed specifically for American clarinets using the A440 pitch but is very popular with all players.
The 5RVL 13 series is also available as a traditional mouthpiece and as a profile 88.