This part is a kind of semiconductor called 5KP18CA.

Function of this product has 5000W TRANSIENT VOLTAGE SUPPRESSOR.

Manufacturers : Diodes Incorporated

Image and pinout :

Some of the text within the PDF file :

5KP5.0(C)A(S) - 5KP240(C)A(S) 5000W TRANSIENT VOLTAGE SUPPRESSOR Features · · · · · · · 5000W Peak Pulse Power Dissipation 5.0V - 170V Standoff Voltages Glass Passivated Die Construction Uni- and Bi-directional Version Available Excellent Clamping Capability Fast Response Time Plastic Case Material has UL Flammability Classification Rating 94V-0 A B A C D 5KP Dim A B C D Min 25.40 ¾ 0.95 ¾ Max ¾ 8.60 1.07 9.53 5KW Min 25.40 1.20 ¾ Max ¾ 9.00 1.30 8.00 Mechanical Data · · · · · Case: 5KP/5KW, Transfer Molded Epoxy Terminals: Solderable per MIL-STD-202, Method 208 Polarity Indicator: Cathode Band (Note: Bi-directional devices have no polarity indicator.) Marking: Type Number Weight: 2.1 grams (approx.) All Dimensions in mm “S” Suffix Designates 5KW Package No [ ... ]

5KP18CA PDF Datasheet Download