This SDCW2012-2-121TF is a common mode choke or filter manufactured by Sunlord. It comes in an 0805 (or 805) size package, and is RoHS compliant. The signal line has a current rating of 370mA. It is used as a line filter for suppressing or blocking differential mode noise (including conducted noise) in switching power supplies and electrical equipment. It is intended for differential-mode interference from noise current sources, such as AC line filter applicatioins.