Product Information: Evans Hydraulic tom batter heads give you the fat, deep, short sound pioneered by rock and roll drummers in the 1970s. Made with a thin layer of oil between two plies of 7 mil film, these heads not only suppress unwanted overtones but are also famously easy to tune. Hydraulics have a defined attack, short sustain, and dark tonal character. Product Features: Evans Hydraulic drumheads are the only heads on the market with a thin layer of oil between two plies of film to suppress unwanted overtones. Known for a fat, deep, short sound reminiscent of early rock n roll. Two plies offer maximum durability. Evans drumheads feature Level 360 Technology to provide ease of tuning, extended pitch range, and optimum quality of sound. For more information and specifications, please refer to the manufacturers website