The CST series of photoelectric sensors from Carlo Gavazzi are a family of inexpensive, general purpose through beam sensors in an industry standard 18mm cylindrical PBTP housing. They are useful for simple applications where a basic sensor provides adequate sensing performance. The sensors are simple to use and no adjustments are necessary. The output is a 4 wire complementary (NO and NC) output in NPN (current sinking) or PNP (current sourcing).