Magnetic laboratory stirrers are ideal for mixing relatively small volumes of a solvent that is not viscous. However, magnetic stirrers are generally not capable of mixing volumes greater than 4L or for stirring viscous solutions. Overhead laboratory stirrers, by contrast, are extremely useful in situations where more than a small volume of a liquid needs to be mixed, or for when the solution involved is too viscous to be mixed using a simple magnetic stirrer. Traditional, or analog, overhead stirrers are adequate for a great number of stirring situations. However, for situations in which greater speed precision is needed, or when knowledge of the true stirring speed is required, a digital overhead stirrer can offer many advantages.