This is a Spex model 1870B spectrometer. It features a focal length of 0.5 meters and fully adjustable input and output slits. The input slit is a type 1451N and includes an additional slider to adjust the slit height in steps. The output slit is a type 1451X mounted on a type 1871 adapter plate. On the output slit is a Products for Research PMT housing with an RCA 4832 PMT installed. The two collimation mirrors have a very faint haze – no cleaning has been attempted! The grating is a B&L type 35-23-06-960 with 1200 g/mm and a blaze angle of 26 degrees, 45 minutes. The grating appears to be in near-flawless condition – no haze or scratches of any kind. Controller for grating position will need to be sourced separately. There also appears to be a motor drive for scanning the input slit. Connection is via a BNC cable. Overall condition of the instrument is extremely fine. Serial number is 3513.