The MI 3299 High voltage Demonstration Box 10 kV has been developed for demonstration purposes at high voltage insulation diagnostics. It simulates typical electrical insulation usually met in the industrial environment. It is equipped with high quality resistors in different ranges, high voltage capacitors and a discharge facility to simulate a breakdown phenomenon in gases. Additionally measurements of polarization index (PI), dielectric discharge (DD) and dielectric absorption ratio (DAR) can be demonstrated. Packed with all these features the demonstration box is also well suited for basic calibration of DC high voltage insulation resistance measuring instruments.