HT Instruments Probe & Test Leads Jack plug 622923 - HT Instruments 1009160, HT Instruments offers the 404-IECB jack plug, featuring a 4 mm socket and jack connector, designed for CAT III 1000 V and CAT IV 600 V applications. This blue connector is an essential measuring accessory for multimeters and other testing instruments. Ideal for electrical testing, it ensures reliable connectivity in a variety of measurement scenarios. HT Instruments 1009160 Electrical Connector 4mm CAT III 1000V Blue