... 4 optic axis.Black plastic shell.It can install some narrow space. We can also produce this type 6 eys ... than 2 sets of devices.Fault self-check, function, power failure stop, innercomponent fault stop, connection fault stop, objectinvading ... supplying powerful controlfunction.Replaceable for similar products made by SICK,STI, KEYENCE,Honeylell Corp. Minisize area secure sensor can use for Elevators