Single Photon Counting Modules (SPCMs) are specialized devices used in various scientific and industrial applications to detect and count individual photons. These modules utilize highly sensitive photodetectors, such as avalanche photodiodes (APDs) or photomultiplier tubes (PMTs), coupled with sophisticated electronics to achieve single-photon detection capabilities. They are crucial in fields like quantum optics, fluorescence spectroscopy, biophotonics, and quantum communication, where detecting and analyzing single photons is essential for accurate measurements and experiments. Generally, basic SPCM models with lower detection efficiencies and standard timing resolutions can start from a few hundred dollars, while more advanced modules with higher performance specifications can range from several thousand to tens of thousands of dollars. When purchasing these modules, assess the specific application requirements such as detection efficiency, timing resolution, spectral range, and integration capabilities to ensure the chosen module meets the project's needs. Additionally, consider the compatibility of the SPCM with existing experimental setups or instrumentation.