What is this black knob on top of the DemerBox?

What is this thing on top of the DemerBox? Should I try to remove it?

We get lots of questions about the black valve on top of the DemerBox. This is called the Pressure Equalization Valve (also known as a Purge Valve). It consists of a housing with a hole through it that is covered with a thin Gore-Tex® membrane. 

According to the GoreTM tech sheet: “The microporous expanded polytetraflouroethylene (ePTFE) membrane continuously allows the free passage of gases and vapors, equalizing the pressure differential between the enclosure and ambient before it builds to the point that a seal is compromised. Water, dust and dirt are repelled by the hydrophobic membrane, thereby protecting expensive and sensitive electronics."

The red tag is a permanent attachment on the purge valve so please don't try to remove it. It's how you know you're using an official Pelican case.