Overhead stirrer for stirring medium-viscosity liquids (max 25000 mPa per sec). It has two easy-to-see digital displays indicating the actual and set speeds. Its dynamic and powerful motor of proven durability and sturdiness is controlled by a microprocessor that keeps the speed constant, even when the viscosity of the stirred liquid changes. Speed pre-selection from 50 to 2000 rpm. Progressive start-up prevents the stirred liquid from coming out of the beaker. A safety system protects the instrument from “overloads” in case the motor malfunctions or jams. The safety chuck without key and technologies adopted ensure safe operation and ease of use with minimum occupied space and a light weight.