For those of you who do not know what a doo rag is, it is a headpiece welders wear under their welding helmet. It looks very much like a biker's bandana, only it is made specifically for welding, with added features like sweat absorption.
I wear this doo rag at work, as you might have guessed. I have several of them that I rotate, bringing used ones home for washing. They are made by Comeaux Caps, a good brand that knows what a welder needs. The doo rags are universal size, you adjust the fit when you tie the ends up on the back of your head. They help th secure the helmet and keep sweat out of my eyes.
The doo rags are available in different designs like camouflage, solid blue, or stars and stripes. Since you wear it under the helmet, the design does not matter that much though.