7 CFR § 51.776 - Slightly rough texture.

Slightly rough texture means that the skin may be slightly thick but not excessively thick, materially ridged or grooved. “Slightly thick” means that the skin thickness does not average more than 5/8 inch (15.9 mm), on a central cross section, on a grapefruit 4 1/8 inches (104.8 mm) in diameter.