Screwdriver

This is something I only found out about recently although I've always had one of these at home.

Have you ever seen a screwdriver with a white semi-transparent grip that had a red cap on it? The ones that seem weirdly complex for a simple screwdriver? Apparently they are used to tell if a screw penetrated an electrical wire in the wall. If it did, the screwdriver will light up and you'll know that you've messed up big time.