The N1411B is a 3 m cable to connect 4-pin interlock plug of B2985A/87A to the 6-pin circular plug. It can be used in N1299A-301 Evaluation kit when the furnished 1.5 m cable is short.
3 m cable with 4-pin interlock plug and 6-pin circular plug
Converting B2985A/87A’s 4-pin plug to 6-pin circular plug