1 pair Expansion microphones.

Works with: Konftel 250, Konftel 300, Konftel 300IP, Konftel 300Wx, Konftel 300M, Konftel 55W

Increases the range from 30 square metres up to 70 (750 sq ft). Connection cables in two lengths, 1.5 metres (4 ft) and 2.5 metres (8 ft) included.