This was removed from an interferometer system. Consists of a HP 10701A 50% beam splitter (which reflects one half of the total incoming laser beam and transmits one half) and an HP 10707A Beam Bender (a 100% reflective mirror that turns the direction of the laser 90 degrees). The two pieces each measure 25x25x25mm and can be easily removed from the mounting assembly if you wish. The entire mounting measures 95mm x 58mm x 50mm and with the attached spring loaded piece stands 135mm high. Used but in great condition!