This part is a kind of semiconductor called RU6055S.

Function of this product has N-Channel Advanced Power MOSFET.

Manufacturers : Ruichips

Image and pinout :

Some of the text within the PDF file :

Features • 60V/60A, RDS (ON) =9mΩ (Typ.) @ VGS=10V • Ultra Low On-Resistance • Fast Switching • 100% avalanche tested • 175°C Operating Temperature • Lead Free,RoHS compliant RU6055S N-Channel Advanced Power MOSFET MOSFET Pin Description TO-263 Applications • Switching Application Systems N-Channel MOSFET Absolute Maximum Ratings Symbol Parameter Common Ratings (TA=25°C Unless Otherwise Noted) VDSS Drain-Source Voltage VGSS Gate-Source Voltage TJ Maximum Junction Temperature TSTG Storage Temperature Range IS Diode Continuous Forward Current Mounted on Large Heat Sink IDP 300μs Pulse Drain Current Tested ID Continuous Drain Current(VGS=10V) PD Maximum Power Dissipation RθJC Thermal Resistance-Junction to Case Drain-Source Avalanche Ratings ③ EAS [ ... ]

RU6055S PDF Datasheet Download