This part is a kind of semiconductor called 1N5956B.

Function of this product has 1.5 Watt Zener Diode 11 to 200 Volts.

Manufacturers : Micro Commercial Components

Image and pinout :

Some of the text within the PDF file :

MCC Features Glass Passivated Junction Low Profile Package Low Inductance Built-in Strain Relief
  omponents 21201 Itasca Street Chatsworth    !"# $ %    !"# 1N5926B THRU 1N5956B 1.5 Watt Zener Diode 11 to 200 Volts DO-41G • • • • Maximum Ratings & Thermal Characteristics Ratings at 25°C ambient temperature unless otherwise specified. Parameter Forward Voltage at IF=200mA Power Dissipation at TL = 75°C Pwak forward Surge Current 8.3ms single half sine/square wave Junction Temperature Storage Temperature Range Symbol VF Value 1.5 Unit V D Ptot 1.5 (1) W A Cathode Mark B D I FSM 10 Amps C Tj -55 ~ +150 o C DIMENSIONS TSTG -55 ~ +150 o C INCHES DIM MIN A B C D 0.166 0.080 0.026 1.000 MAX 0.205 0.107 0.0 [ ... ]

1N5956B PDF Datasheet Download