This is a simple, very common rectifier diode. Often used for reverse voltage protection, the 1N4001 is a staple for many power, DC to DC step up, and breadboard projects. 1N4001 is rated for up to 1A/50V.

If you need a bunch of these, you can get good bulk discounts on Digikey, part # : 1N4001-TPMSCT-ND

Documents:Datasheet