This part is a kind of semiconductor called 1N5987A.

Function of this product has ZENER DIODES.

Manufacturers : EIC

Image and pinout :

Some of the text within the PDF file :

1N5985A - 1N6031A VZ : 2.4 - 200 V PD : 500 mW FEATURES : * Extensive selection from 2.0 V to 200 V * Standard zener voltage tolerance is ± 10%. * Other tolerances are available upon request. * Pb / RoHS Free MECHANICAL DATA : * Case: DO-35 Glass Case * Weight: approx. 0.13g Certificate TH97/10561QM Certificate TW00/17276EM ZENER DIODES DO - 35 Glass (DO-204AH) 0.079(2.0 )max. Cathode Mark 0.020 (0.52)max. 1.00 (25.4) min. 0.150 (3.8) max. 1.00 (25.4) min. Dimensions in inches and ( millimeters ) Maximum Ratings and Thermal Characteristics Rating at 25 °C ambient temperature unless otherwise specified. Rating Power Dissipation Maximum Forward Voltage at IF = 200 mA. Thermal Resistance Junction to Ambient (Note 1) Thermal Resistance Junction to Lead (Note 1) Operating and Storage [ ... ]

1N5987A PDF Datasheet Download