I need an audio crossover cable to connect two bases together by way of the 4-wire ports.

ProductionWireless (818-840-9311) sells 3 foot long, 4W Audio Crossover Cables Black, marked “A” and “B“ in pairs Partnumber PWS002-2622These are handy when connecting 4-wire ports together from base to base to such as on the DX200, DX210, DX410, Pro850, Helixnet base module HLI-4W2 and some older models of Freespeak II and CellCom bases.