My laptop bag has scared TSA security personnel at several airports recently, requiring manual bag inspections each time. And when it happened again this week I finally figured out what it is that was freaking them out when the bag went through the x-ray machine - it's the spare laptop battery I always carry. This would never be an issue if the battery were inside the laptop, but the spare battery (depending on how it is laying in the back) can catch attention. But, TSA issues aside, look at the shape of the battery. You just have to wonder - what on earth was IBM thinking?