The EC2 features a Sound Shaping Technology ring mounted underneath two plies of 7mil film. By controlling edge vibration (instead of eliminating it), the ring isolates and damps higher overtones, enhancing low-end and attack, and enabling a broader tuning range.
EVANS EC2 SST B16EC2S features: tom batter head size: 16" coated 2-ply individual damping with SST (Sound Shaping Technology) balanced pre EQ´d sound more attack and sustain simple tuning