Check carry gaps before choosing a four-iron
The instructor recounts carrying a five-iron 200 yards and a four-iron only 207-208, then looking for a four-iron carry around 215. The discussed 21-degree design uses a cavity milled deep toward the sole to lower the center of gravity, launch high, and add ball speed through stronger loft.
Channel: Club Champion
Watch official source at 6:16Why this context matters
The carry numbers are the instructor's personal gapping example.