Quick Comparison - The GR 66.9 Series cup diameter is similar to a conventional 1 1/2 diameter.  These offer the 1 1/2C player a familiar feel but with a more efficient design, full of overtones and better matched to both Bb and C trumpet.

L66.9 C-Rim is semi flat with a bite that is sharp, the alpha is medium low and this mouthpiece is for a more open trumpet or designed for C trumpet. 

Standard GR Symphonic Blank and length with standard throat bore, and #3 BB, also available in the Classic Blank or Symphonic Blank with the traditional overall length and different backbore as a special order.

L66.9 B- Rim is semi flat with a bite that is sharp, the alpha is medium low and this mouthpiece is for a more open trumpet or designed for Bb trumpet. 

Standard GR Classic Blank and length with standard throat bore, and #3 BB, also available in the Symphonic Blank or Symphonic Blank with the traditional overall length and different backbore as a special order.

L66.9C 2.4-Rim is semi flat with a bite that is sharp, the alpha is medium low and this mouthpiece is for a more traditional trumpet or designed for C trumpet to achieve a traditional sound with full harmonic spectrum of overtones. 

Standard GR Symphonic blank and length, larger throat bore, and #3BB, also available in the Symphonic Blank with the traditional overall length, GR Classic Blank with Standard length or GR Classic Blank with traditional overall length and different backbore as a special order.

L66.9B 2.8-Rim is semi flat with a bite that is sharp, the alpha is medium low and this mouthpiece is for a more traditional trumpet or designed for Bb trumpet to achieve a traditional sound with full harmonic spectrum of overtones. 

Standard GR Symphonic blank and length, larger throat bore, and #3BB, also available in the Symphonic Blank with the traditional overall length, GR Classic Blank with Standard length or GR Classic Blank with traditional overall length and different backbore as a special order.