Thorlabs' SPCNT Single Photon Counting Device recognizes signal pulses originating from a connected single photon detector. The results are shown numerically as counts or frequency on the built in display or sent to a connected PC for display and analysis. The SPCNT counter is compatible with Thorlabs' SPDMA single photon detector with adjustable gain and the SPDMHx series of detectors series of detectors with fixed gain.