Evans Genera HD Dry snare drumheads are made with precision-drilled dry vents around the perimeter of the head to reduce overtones and control sustain. These drumheads feature two plies of film, an outer ply of 5mil film, an inner ply of 7.5mil film, and a 2mil overtone control ring on the underside that floats with the head, removing excessive overtones and controlling sustain. The HD Dry model uses Evans Level 360 Technology for ease of tuning, extended pitch range, and optimum quality of sound.