 Digital System to System Interface adapter - 2 channels of RTS TW to 4 wire conversion or 1 channel of RTS TW to 2 wire conversion (replaces SSA-424 & SSA-424A). Two Independent Hybrids Automatic Nulling Peak Reading Level Meters Direct ADAM/ZEUS Audio Connection Transformer Isolated Call Signal Option Half-Rack Wide, 1 RU High Universal Power Pack |