This part is a kind of semiconductor called 1N6319.

Function of this product has 500mW GLASS ZENER DIODES.

Manufacturers : Microsemi

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Some of the text within the PDF file :

1N6309 thru 1N6355D Available on commercial versions VOIDLESS HERMETICALLY SEALED 500mW GLASS ZENER DIODES Qualified per MIL-PRF-19500/533 DESCRIPTION This Zener voltage regulator series is military qualified and is ideal for high-reliability applications where a failure cannot be tolerated. These industry-recognized 0.5 watt Zener voltage regulators are hermetically sealed with voidless-glass construction using an internal metallurgical bond. It includes Zener selections from 2.4 to 200 volts in standard 5% tolerances as well as 1% and 2% tolerances. They are also available in surface-mount packages. Microsemi also offers numerous other Zener products to meet higher and lower power ratings in both thru-hole and surface mount packages. Important: For the latest information, visit our w [ ... ]

1N6319 PDF Datasheet Download