Giardinelli 6FL vs GR Technologies G66FD Radtke
The GR Technologies G66FD Radtke has a wider cup diameter, the Giardinelli 6FL features a deeper cup.
The internal diameter of the cup, measured at the widest point inside the rim.
Mouthpiece A
Giardinelli 6FL
• Flugelhorn
Cup diameter16.70 mm / 0.6575 in
vs
Mouthpiece B
GR Technologies G66FD Radtke
• Flugelhorn
Cup diameter16.76 mm / 0.6598 in
Cup Diameter
The GR Technologies G66FD Radtke has a cup diameter of 16.76 mm / 0.6598 in compared to 16.70 mm / 0.6575 in on the Giardinelli 6FL — a difference of 0.06 mm / 0.0024 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.