This part is a kind of semiconductor called 1N5231.
Function of this product has ZENER DIODES.
Manufacturers : General Semiconductor
Image and pinout :
Some of the text within the PDF file :
1N5225 THRU 1N5267 ZENER DIODES FEATURES DO-35 min. 1.083 (27.5) ♦ Silicon Planar Power Zener Diodes ♦ Standard Zener voltage tolerance is ± 5% with a “B” suffix. Other tolerances are available upon request. max. ∅.079 (2.0) Cathode Mark min. 1.083 (27.5) ♦ These diodes are also available in Mini-MELF case with the type designation ZMM5225 ... ZMM5267, SOT-23 case with the type designation MMBZ5265 ... MMBZ5267 and SOD-23 case with the types designation MMSZ5225 ... MMSZ5267. max. .150 (3.8) max. ∅.020 (0.52) MECHANICAL DATA Dimensions are in inches and (millimeters) Case: DO-35 Glass Case Weight: approx. 0.13 g MAXIMUM RATINGS Ratings at 25°C ambient temperature unless otherwise specified. SYMBOL VALUE UNIT Zener Current (see Table “Characteristics”) Power [ ... ]