I'm not talking about standard batting kit here. I'm talking about things that aren't part of your normal cricket gear, like gilchrist and the ping pong ball, or one of the waugh brothers and the red rag.
For me it's a bandanna. When I first got a lid at the tender age of 12, my dad bought one for me to grow into, so I had to wear a sweatband to get it to fit. Once I grew out of it, I binned the sweatband and got a perfectly fitting helmet. However something was amiss, and didn't feel right, I couldn't bat. I tried a bandanna on underneath the lid and hey presto, everything felt right in the world! I started off wearing my ayrtek without one but it never felt right, until wearing it with a bandanna today.