This part is a kind of semiconductor called 2SD587.

Function of this product has Silicon Triple Diffused Transistor.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

1SMA4741 thru 1SMA200Z SURFACE MOUNT SILICON ZENDER DIODE PRODUCT SUMMARY 1.0 Watts Surface Mount FEATURES For surface mounted applications in order to optimize board space Low profile package Built-in strain relief Glass passivated junction Low inductance Typical IR less than 5.0uA above 11V High temperature soldering guaranteed: 260°C / 10 seconds at terminals Plastic package has Underwriters Laboratory Flammability Classification 94V-0 SMA/DO-214AC MECANICAL DATA Case: Molded plastic over passivated junction Terminals: Pure tin plated lead free, solderable per MIL-STD-750, Method 2025 Polarity:Color Band denotes positive end (cathode) Standard packaging: 12mm tape (EIA-481) Weight: 0.002 ounces, 0.064 gram Dimensions in inches and (millimeters) Pb-free; RoHS-compliant MAXIMUM RAT [ ... ]

1SMA4758 PDF Datasheet Download