This wideband coupler enables either 1310nm or 1550nm wavelength optical telecommunication traffic traveling along an optical fibre to be split off and separately monitored or re-transmitted along another optical fibre. The coupler is of high precision construction and housed in a rugged, rectangular style, strong and sturdy housing. Output leads, of 1100mm length, are terminated with A/SC connectors. (Both the input and output leads are the same length). This coupler meets the environmental performance detailed in GR-1209 and GR-1221. It offers: good uniformity; low excess loss and high performance, over a wide temperature range, to achieve a service lifetime of 20 years. The couplers split ratio is 1 x 2, 50:50 split. Various couplers with different split ratios are available separately. Also, any required length of both input and output leads can be supplied separately.