The Gen 2 26F is one size smaller in diameter than a PT65. Wedge F tuba cups are similar to a PT65 cup. They have a shallow, modified V shape, which provides an excellent balance of clarity and projection with an even response in all registers and a round, full tone.
ID: 1.26 inches at .05 inches into the cup (32 mm)
OD: 1.86 inches (47.24 mm)
Throat: .310 inches (7.87 mm)