DW 9000 Series Hi-Hats utilize a patented
Double Eccentric Cam
(shown within photo #3) that increases the sensitivity of the footboard in relation to cymbal movement, resulting in a unique, incredibly fast and responsive feel. (U.S. Patent No. 5266733)
The Infinitely Adjustable Locking Spring Tension feature (also shown within photo #3) allows for precise adjustment to offset the weight of the top cymbal, creating a customized feel. (Infinite Adjusting Spring Tension on 9500 and 9502LB)