The Robert Tucci RT-88+ is a heavy shell mouthpiece that has the same basic specifications of the RT-88. The major difference is that the heavy shell model ensures that the sound does not dissipate in the extreme loud dynamics. It also creates a darker more centered sound.
Specifications
Cup: Inner diameter 33.5mm/1.32in, wide deep cup
Rim: 7mm/0.28in, well defined inner edge
Bore: 8.1mm