This part is a kind of semiconductor called 1N3208.
Function of this product has Silicon Rectifier Diodes.
Manufacturers : Vishay
Image and pinout :

Some of the text within the PDF file :
www.vishay.com 1N3208 Series Vishay Semiconductors Silicon Rectifier Diodes, (Stud Version) 15 A DO-203AB (DO-5) PRODUCT SUMMARY IF(AV) 15 A FEATURES • Low thermal impedance • High case temperature • Excellent reliability • Maximum design flexibility • Can be made to meet stringent military, aerospace and other high reliability requirements • Material categorization: For definitions of compliance please see www.vishay.com/doc?99912 MAJOR RATINGS AND CHARACTERISTICS PARAMETER TEST CONDITIONS IF(AV) IFSM I2t I2t VRRM TJ Note (1) JEDEC registered values TC 50 Hz 60 Hz 50 Hz 60 Hz Range VALUES 15 (1) 150 (1) 239 250 (1) 286 260 3870 50 to 600 - 65 to 175 UNITS A °C A A2s A2s V °C ELECTRICAL SPECIFICATIONS VOLTAGE RATINGS TYPE NUMBER 1 [ ... ]
1N3208 PDF Datasheet Download
