Schutzinger 1000V CAT IV 4mm Socket Safety Test Probes. Schutzinger CAT IV safety test probes offered in red and black, featuring a 4mm axial socket and over-moulding protection. These safety test probes are rated at 16A and 1000V with nickel plated contact parts. Rated at 16A 1000 V CAT IV Operating temperature -25 to 80 °C Transition resistance less than 5 m