The mechanics of a guitar allow the tuning pegs to be turned. The guitar is tuned here. They consist of a wing, on which you can grip and turn the mechanics, and the actual mechanics. Open mechanics are mostly found on classical or vintage guitars. When the mechanisms are closed, a cover is simply mounted on the gearwheels. Thus, they are protected from light soiling. With electric guitars you usually see encapsulated machine heads. The threaded part is completely encapsulated and no dirt can penetrate.