 Any timpani equipped with such a system may be considered "machine timpani", although this term commonly refers to drums that use a handle connected to a spider-type tuning mechanism.By far the most common type of timpani used today are pedal timpani, which allows the tension of the head to be adjusted using a pedal mechanism.Typically, the pedal is connected to the tension screws via an assembly of either cast metal or metal rods called the "spider".