The 4 mm sliding sleeve system has a sliding protection of the 4 mm contact (plug) and prevents short circuits and electrical shocks. The system can be used in combination with any 4 mm system. Since the contact protection is sliding, it can be used till 60 VDC according to IEC 61010. Exceptionally on the side of the instrument till DC 150 V, CAT II, for equipment that is still not provided with fully-insulated connections (see IEC 61010 regulations).
A good compromise to use with older test equipment…