Series adjustable resistors CWM they are enclosed in a housing made of flame retardant V0 plastic, with a cermet resistive element, which is much more durable than typical carbon tracks. The resistors have a linear characteristic (A), they are adapted to work at high voltage, e.g. for cooperation with a high-voltage duplicator. Potentiometers with resistance tolerances of 5% and 10% are available on special request.