What is this plug?

I just bought this used board and it has this plug in it, not sure what is. The guy I bought it from didn't own the board so he wasn't exactly sure what it was. I was told that it's to relieve internal pressure in the board while traveling airborne. I have found other plugs online such as "gore-tex" plugs, but they don't look like the one on my board. From the information I found online, these vent plugs are used for wood surfboards and to prevent delaminating due to heat. The plug on my board has red fabric material in the middle and looks like it can be unscrewed by the grooves on each side. Really looking to find out what this plug is for and if anyone has any information on the plug I have on my board, it'd be much appreciated.