I bought these Gel pads and also a set of Millennium Sound Control Rings which are half the price for my new studio kit in a smallish room - my view if the rings really take out unwanted tones whilst leaving the drums crisp and vibrant whereas the gel can over damp and leave the drums a bit flat. I am sure this varies by kit and actually on my snare, one gel pad with a control ring sounds great but I have not used them on the cymbals (used Cympad Moderators instead) or Toms (just control rings).
A personal thing I know but hope it helps someone...
Also seems expensive for a bit of mass produced squidgy gel but suppose packaging etc takes a bit too... hence dropped a star for value.