The Testing station detects the various properties of the work pieces inserted into it. It differentiates work pieces with the aid of an optical and a capacitive sensor. A retro-reflective sensor monitors whether the operating space is free before the work piece is raised via a linear cylinder. An analogue sensor measures the height of the work piece. A linear cylinder guides correct work pieces via the upper air slide to the neighboring station. Faulty work pieces are rejected via the lower air slide.