What do a traffic light and a bat symbol cast onto the night sky have in common?

What a vending machine with an accent might say when pointing out a writing utensil to a gentleman.

I come in pairs, but never speak. I have a sole, but cannot walk. I keep your feet cozy, yet I'm often lost.

This word usually just has one letter in it but I guess it could have more if you stuff them in there and have more stamps.

Pick it, grind it, swing it, and now for fun, throw it at a target.