Multimode optical fibre links, that use laser based transmitters, may be limited in bandwidth to values less than half those of the over-filled launch bandwidth. Mode conditioning patch cords are designed to allow the use of laser transmitters in 62.5/125 (OM1) or 50/125 (OM2) multimode fibre optic cabling systems. These assemblies allow long wavelength 1300nm signals to be transmitted, over good quality fibre, at distances of up to 550m. The Netprom mode conditioning cable assembly, improves performance by moving the singlemode launch to an offset position, increasing the mode fill and reducing DMD.