Design News has an article on shaker flashlight knockoffs from China and how they are poorly designed. One of the commenters had an interesting story.
These are usually referred to as \"wanker\" flashlights, and no you have to look it up yourself. A friend who has a battery store thought these would be good for promotional give aways until I mentioned the name a friend in the UK had called them and the fact he was in business to sell batteries.. Trying to keep a straight face he got a customer to try one which promptly broke. These real cheap ones had a plastic tab as stops. Needless to say they were gone the next time I was there.The moral of this story? Low price isn't everything if the device doesn't work well. The other moral? Wasting your money on a cheap imitation could move you into the wanker category. Go for the real thing.