This part is a kind of semiconductor called 1N5664.

Function of this product has Silicon Avalanche Diodes.

Manufacturers : Littelfuse

Image and pinout :

Some of the text within the PDF file :

Silicon Avalanche Diodes 1500 Watt Metal Axial Leaded Transient Voltage Suppressors 1N56 Series FEATURES • Hermetically sealed • Breakdown voltage range 6.8 - 200 volts • Glass passivated junction • Excellent clamping capability • Low zener impedance •100% surge tested •-55°C to +150°C •Uni-polar ® 6 SILICON DIODE ARRAYS Min 31.8 Max 5.33 7.5 9.0 Min 25.4 Max 0.8 5.58 MAXIMUM RATING •Peak Pulse Power (Ppk): 1500 Watts (10 x 1000µs)@25°C (see diagram on page 3 for wave form) •1 watt steady state •Response time: 1 x 10-12 seconds (theoretical) •Operating & storage temperature: -55°C to +150°C MECHANICAL CHARACTERISTICS •Case: Metal hermetically sealed DO-13 package •Terminals: Axial leads, solderable per MIL-STD-202 Method 208 •Solderable leads = 2 [ ... ]

1N5664 PDF Datasheet Download