Evans HD Genera Dry. An extremely versatile 2-ply coated head with dry vents and an overtone control ring that delivers diverse sounds. A basic sound that's punchy, defined, and loud, with a dry, controlled sustain. 2-ply coated head. Overtone control ring. Dry vents. Outer ply: 7.5mm. Inner ply: 5mm. Control ring: 2mm.