GR Compu-Bal trumpet mouthpiece 67 rimThe GR 67 Series cup diameter is similar to a conventional 1 1 2 to 1 1 4 diameter. The 67L is a very popular choice for 1 1 2C players looking for more core in their sound with more secure articulations in a more efficient design. Classic Blank is standard. Symphonic Blank is standard on the C** and C models. Classic Blank is standard on the C T and B T Models. G Rim Models G67LX, G67L Same cups as their standard counterparts but with the slightly