The SEI (Salford Electrical Instruments) exposure photometer is a renowned vintage, high-precision spot meter produced from the late 1940s to the 1960s. It acts as a narrow-angle, 1° comparison photometer used to measure scene brightness by comparing a subject against an internal lamp. It is known for extreme accuracy, used by professional photographers and cinematographers.  This one on auction is not tested for working . The meter looks good and complete. Please see all pictures as they are part of the description.