If you have a clamp on amp meter, you know you can only put it over one wire or it doesn't work.  This plugs into the wall, you plug the item you are testing into this, and then you can check draw.  Too easy.  It has a 1x and a 10x opening.  The 10x is great for low draw stuff.  If your clamp meter didn't come with one of these, get this one.