Hi-Hat

Hi-Hat - A hi-hat, or hihat, is a type of cymbal and stand used as a typical part of a drum kit by percussionists in R&B, hip-hop, disco, jazz, rock and roll, house, and other forms of contemporary popular music. Other recent developments include the X-hat (fixed, closed, or half-open hi-hats) and cable-controlled or remote hi-hat. 

The hi-hat consists of two cymbals that are mounted on a stand one on top of the other and clashed together using a pedal on the stand. A narrow metal shaft or rod runs through both cymbals into a hollow tube and connects to the pedal. The top cymbal is connected to the rod with a clutch, while the bottom cymbal remains stationary resting on the hollow tube. The height of the top-cymbal (open position) is adjustable.
When the foot plate of the pedal is pressed, the top cymbal crashes onto the bottom cymbal (closed hi-hat). When released, the top cymbal returns to its original position above the bottom cymbal (open hi-hat). A tension unit controls the amount of pressure required to lower the top cymbal, and how fast it returns to its open position.