The hairspring is a flat, spiral spring that consists of 12 to 15 turns, weighs around 1 milligram, and is approximately 0.03 millimeters thick. Hairsprings serve a single purpose: when they coil and uncoil, hairsprings propel a balance wheel that spins around its axis. This balance is a flywheel and is meant to accumulate the energy provided by the hairspring. Both are made so this oscillation is as regular and repeatable as possible in order to become a stably recurring phenomenon. Because of the reliability of hairsprings, they are frequently used in watches and master clocks, which are used to measure time in very small increments. Wheels and pinions convert the oscillation into seconds, minutes, hours, and so on. Because hairsprings transform the energy they receive into information, it is considered a mechanical processor.