PaulS:
That is USELESS information. Post a link, not some catalog number.
if you search in intenet you will found what type of sensor is, but whatever.
http://www.arduiner.com/en/infrared-obstacle-sensors/577-tunable-350cm-e18d50nk-infrared-obstacle-avoidance-sensor-close-switch-smart-car-3809200622756.html
the description is down below, or that link
http://www.electronicaestudio.com/docs/SHT-015d.pdf