Bar across the guitar hole?

um yea i was just watching some vids on youtube and i noticed that some people have this bar type thing going across the hole in the middle of the guitar...

wut is it and wut does it do???

A bar over the hole of the guitar would be a pickup. It's an electronic device that allows the amplifiers to "pick up" the sound from the guitar.

its a pickup for acoustic guitars

It stops the hole falling out :o)

Misread your question, what the first guy said. It sounds like a pickup for an acoustic/electric combo.