The L-B4L rim is semi-round, very soft, and wide enough to offset lip swelling. There is some undercut for chop room. The cup is medium to medium shallow, with a rounded entrance to the throat that is very receptive to good air flow. The cup and rim were designed to have a cushioned feel without sacrificing range or intonation. The throat is a #27, the throat cylinder length is enhanced, and the backbore is a Legends S. Slotting is excellent with the L-B4L. The design elements of this model maximize endurance and range for the player, and work together to allow a big sound in any register. This mouthpiece is popular both with full-time lead players, and also with classical players who occasionally need a smaller, more shallow lead mouthpiece. Use the L-B4L when you want to play both technical legit music and screaming lead!