typically have between one and four speeds. Fans with lights usually have a second pull chain which is to control light, and it's usually on/off, but sometimes it's three way, in which case it would be some lights, other lights, all lights, and off. Some fans, usually outdoor rated or Canadian, have another pull chain to change direction. Variable-speed control. During the 1970s and into the mid-1980s, fans were often produced with a solid-state variable-speed control. This was a dial mounted either on the body of the fan or in a gang box at the wall, and when turned in either direction, continuously varied the speed at which the blades rotated—similar to a dimmer switch for a light fixture. A few fans substituted a rotary click-type switch for the infinite-speed dial, providing a set number of set speeds (usually ranging from four to ten). Different fan manufacturers used variable-speed controls in different ways: The variable-speed dial controlling the fan entirely; to turn the fan on, the user turns the knob until it clicks out of the "off" position, and can then choose the fan's speed. Variable speed pull-chain. This setup is similar to the variable-speed dial discussed above, except that a "dual chain" setup is used to turn the potentiometer shaft. A pull-chain present along with the variable-speed control; the dial can be set in one place and left there, with the pull-chain serving only to turn the fan on and off. Many of these fans have an option to wire an optional light kit to this pull-chain in order to control both the fan and the light with one chain. Using this method, the user can have either the fan or light on individually, both on, or both off. Vari-Lo. A pull-chain and variable-speed control are present. Such a fan has two speeds controlled by a pull-chain: high (full power, independent of the position of the variable-speed control), and "Vari-Lo" (speed determined by the position of the variable-speed control). In some cases, maximum speed on Vari-Lo setting is slower than high. Wall-mounted control. Some fans have their control(s) mounted on the wall instead of on the fans themselves; these are very common with industrial and HVLS fans. Such controls are usually proprietary and/or specialized switches. Mechanical wall control. This style of switch takes varying physical forms. The wall control, which contains a motor speed regulator of some sort, determines