It says it is an ambient light sensor, but is it a phototransistor? Something else? It has Vcc and Vout pins. Bonus points if you include a data sheet.

• Yeah you'll want to go to digikey where you can actually see the datasheet for what you are buying. Radioshack used to just mix up a bunch of random crap (PNP transistors - great thanks) for people that have way too much time on their hands. Digikey or mouser is the way to go – cowboydan Aug 20 '15 at 2:31

Maybe this one?

ALS-PDT243-3C/L451 Ambient Light Sensor 5mm T-1

The ALS-PDT243-3C/L451 is an ambient light sensor using a photo transistor in a DIP package.

• Close enough, so I accept it – Alexander M Aug 20 '15 at 20:09

• What, Lower dark current: 0.1uA isn't good enough for you? ;) – DigitalNinja Aug 20 '15 at 16:39