The Agilent 81625B optical heads are specially designed for low PDL , low spectral ripple and high return loss and are used for optical component tests. The optical heads have to be operated with the single (Agilent 81618A) or dual (Agilent 81619A) interface modules. The heads come with a magnetic D-shape adapter and provide a safe stand. They are used in lightwave mainframe models 8163A/B, 8164A/B and 8166A/B.