High Tech Pet Sofa Scram Sonic Scat Pad Pet Deterrent by High Tech Pet Products, Inc

Can you put this under a couch cushion? I want to train the dog to stay off the couch, not stay off the couch when this mat is there.

how long is it

Does this come with batteries? Or do you have to buy them seperately?

I have a long couch. Do I need to buy two?