21 ACESSORIES AND COMPONENTS FOR ELECTRONIC COMMUNICATION, HIGH FREQUENCY AND ELECTRONIC EQUIPMENT -- NAMELY, ADJUSTABLE ROTABLE, SLIDABLE AND SPINDLE-OPERATED RESISTANCES IN SINGLE AND MULTIPLE TYPES, WITH AND WITHOUT SWITCHES, FOR FREQUENCY TUNING WITH CAPACITANCE DIODES, FOR ADJUSTING OPERATION VALUES IN ELECTRICAL, COMMUNICATION, HIGH FREQUENCY AND ELECTRONIC EQUIPMENT