This is a 5g syringe of white heatsink compound (aka thermal grease, thermal paste, thermal goo).
Use this whenever you're connecting a component to a heatsink, it'll really help to dissipate even more potentially damaging heat.

This compound is composed of 50% silicone, 20% carbon, and 30% metal oxide.
It has a thermal conductivity of 1.172 W/(mK), which should be plenty for voltage regulators, MOSFETs, motor drivers, audio amplifiers, etc.

 

Features:

• Color: White
• Thermal Conductivity: 1.172 W/(mK)
• Thermal Impedance: 0.195 -in^2/W
• Specific Gravity: 2.3 @25°C
• Evaporation: 0.001% - 24 hrs @150°C
• Bleed: 0.05% - 24 hrs @150°C
• Moment Beared Temperature: -50-240°C
• Operation Temperature: -30-180°C

Documents:

• MSDS