Level sensors are used to detect liquid or powder levels, or interfaces between liquids. There are two basic level-measurement types: continuous and point or multi-point. Continuous level sensors measure liquid or dry material levels within a specified range and provide outputs which continuously indicate the level. Point level sensors or multi-point sensors mark a specific level and are used generally as a high alarm or switch. These level sensors can also be integrated in a single device to add a low alarm, or to serve as a stepped version of a continuous level. For both types of level sensors, choices for output options include analog voltage signal, analog current signal, frequency or modulated frequency, and alarm or visual indicator.