Our Quad Optical Detector Module includes
four photocell sensors, but occasions may
arise when you need more.  You may wish to
use more than one on a single input to activate
a device from multiple locations, or one or
more may simply become lost or damaged.  
When that happens, this 4-pack of replacement
sensors is the thing for you, and it includes the
same foam mounting pieces that you'll find
with the Optical Detector.
GSP-13  Photocell Light Sensors . . . $2.49