Somewhere in the 90's everyone went to extremely resonant heads, with RIMMS mounts, or other proprietary suspension systems all in the name of "sustain".  Well, if you play rock, and like to record live drums at all, and you can't afford a $3000 maple kit, then you know the pitfalls of this---ringing drums.  I like overtones, and in Jazz, they are desirable, but honestly when I play rock I just want a fat tom sound that decays quickly.  I remember hydraulic heads from high school in the 80's, but I was somehow duped into believing the sound was unnatural and I should get open sounding drumheads.  Well, the caveat being you are always using something to dampen the heads, it makes no sense really.  These things sounded killer right out of the box.  It made my 12" tom and 14" floor tom sound huge, lots of low end.  And hey, they are red and look sick.