This part is a kind of semiconductor called MRF581.

Function of this product has RF & MICROWAVE DISCRETE LOW POWER TRANSISTORS.

Manufacturers : Microsemi

Image and pinout :

Some of the text within the PDF file :

RF & MICROWAVE DISCRETE LOW POWER TRANSISTORS MRF581 MRF581G MRF581A MRF581AG *G Denotes RoHS Compliant, Pb free Terminal Finish Features • Low Noise - 2.5 dB @ 500 MHZ • Gain at Optimum Noise Figure = 15.5 dB @ 500 MHz • Ftau - 5.0 GHz @ 10v, 75mA • Cost Effective MacroX Package Macro X DESCRIPTION: Designed for high current, low power, low noise, amplifiers up to 1.0 GHz. ABSOLUTE MAXIMUM RATINGS (Tcase = 25°C) Symbol Parameter VCEO Collector-Emitter Voltage VCBO Collector-Base Voltage VEBO Emitter-Base Voltage IC Collector Current MRF581 MRF581A 18 15 30 2.5 200 Unit Vdc Vdc Vdc mA Thermal Data P D P D Tstg Total Device Dissipation @ TC = 50ºC Derate above 50ºC Total Device Dissipation @ TC = 25ºC Derate above 25ºC Storage Junction Temperature Range TJmax [ ... ]

MRF581 PDF Datasheet Download