The Agilent HP 86109B is a used Optical Plug-In Module that provides the highest combination of optical and electrical bandwidth required for testing beyond 10 Gb/s. The electrical channel has 50 GHz bandwidth and the optical channel has 40 GHz of bandwidth. 40 GHz of unfiltered optical bandwidth is essential now that return-to-zero (RZ) modulation formats are being used in 40 Gb/s transmission systems under development.