Evans EC series features two plies of film. The outer ply of 7mil and the inner ply of 10mil provides a controlled sound but with resonance and sensitivity at all tuning and dynamic ranges. Sound Shaping Technology (SST) rings on the underside reduce unwanted frequencies and enhances attack. Evans Level 360 technology is incorporated to extend the level playing surface of the drumhead, 360 degrees around the drum. The vertically enhanced collar design guarantees even contact with the critical bearing edge of the drum shell, resulting in: ease of tuning, extended pitch range and optimum quality of sound. Evans Level 360 technology resolves the age-old dilemma of traditional synthetic heads consistently not fitting the drum shell without using considerable force.