Circuitron 800-9202 OS-2 Opto-Sensors (2-Pack)

Opto-Sensors are tiny, light sensitive photocells for use with any Circuitron product that utilizes Opto-Electronic detection. These Opto-Sensors are mounted in the roadbed so that they will be shaded from ambient room light by a passing train.

These will fit between the ties in HO or larger scales, but it may be necessary to remove a tie or shave parts of adjoining ties away in smaller scales.