Evans hydraulic heads , you either love 'em or hate 'em --
First of all these are 2 ply (10 mil) heads , so they are pretty thick giving you less sustain and more durability.
These heads have major attack and less resonance (it doesn't kill the drum's tone like others say), they have a fatter sound so your drums will achieve a deeper warm-ish sound.
A set of nice durable fat sounding drumheads