This part is a kind of semiconductor called 150UR120D.

Function of this product has (150UR Series) STANDARD RECOVERY DIODES.

Manufacturers : International Rectifier

Image and pinout :

Some of the text within the PDF file :

Bulletin I2025 rev. C 10/02 150U(R).. SERIES STANDARD RECOVERY DIODES Features Diffused diode Wide current range High voltage ratings up to 1200V High surge current capabilities Stud cathode and stud anode version Hermetic metal case Stud Version 150A Typical Applications Welders Power supplies Machine tool controls High power drives Medium traction applications Battery charges Free-wheeling diodes Major Ratings and Characteristics Parameters IF(AV) @ TC IF(RMS) IFSM @ 50Hz @ 60Hz It 2 150U(R).. 150 125 235 3000 3140 45 41 600 and 1200 - 40 to 180 Units A °C A A A KA2s KA2s V °C @ 50Hz @ 60Hz V RRM range TJ case style DO205 (DO-8) www.irf.com 1 150U(R).. Series Bulletin I2025 rev. C 10/02 ELECTRICAL SPECIFICATIONS Voltage Ratings Vo [ ... ]

150UR120D PDF Datasheet Download