This part is a kind of semiconductor called 1N4744.

Function of this product has 1.0 Watt Zener Diode 3.3 to 100 Volts.

Manufacturers : Micro Commercial Components

Image and pinout :

Some of the text within the PDF file :

MCC Features l Hermetic Glass Package l Silicon Planar Zener Diodes
  omponents 21201 Itasca Street Chatsworth    !"# $ %    !"# 1N4728 THRU 1N4764 1.0 Watt Zener Diode 3.3 to 100 Volts DO-41G l These diodes are also available in the MELF case with type designation DL4728 thru DL4764. Mechanical Data l Case: DO-41 Molded Glass l Polarity: is indicated by cathode band. l Weight: 0.378 grams (Approx.) Maximum Ratings l l l Operating Temperature: -55 C to +150 C Storage Temperature: -55 C to +150 C o o o o D A For capacitive load, derate current by 20% Cathode Mark B Electrical Characteristics @ 25oC Unless Otherwise Specified DC Power Pd 1.0W TA =100oC Dissipation Peak Forward IFSM See Page 2 Surge Current Thermal RqJA 100oC/W N [ ... ]

1N4744 PDF Datasheet Download