First off, I am a member of ebay and the first lights i bought were fake . i was new i had no ideal . but i was determined to find out the difference first there are three types that the ebay members are selling the shaker that runs off two little power cells.but when the power cells die they have to be replace/ there are varying description on how long they last some say 12 hours ,others say 36 48 who knows  your guess is mine/ second they sell dual powered ones they have power cells and a capacitor and 3 the ones that run off just a capacitor. but all that is fine so they are different types,but what disturbs me most people you manipulation to describe there product. but the bottom line when they say batteries they have power cells that solely power the lights a lot of ebayers dont know what they are selling. a lot members just copy adds ,and dont put much thought in what they are selling, when you buy shake lights see how much stress is put on the faraday principle . a lot of the advertisement is just say good for emergencies a 7 inch light led bulb , but not much more. if i was selling a shake light i would feel comfortable with putting a lot of emphasis on the faraday principle. ask that ebayer questions ,find out what he is really selling if you want a real shake light awake sure they have a capicitorthat is the true testof a shake lights. i sell all three but i am very emphatic on what i am selling. i dont deceive the public if they have batteries i tell them if they have a capicitor i put great emphasus on that. but when you buy something ,know every thing you can about that item . then educate yourself and make an informed decision to buy. but a fake lights that runs solely on batteries ihas a slug for a magnet, a coil that runs nowhere that is not working a printed circuit that all does is meeting point for the batteries to be hooked up to a light. there is nothing wrong with the fake ones but why should ebay members masquarade them as real ones they should be sold at a lot cheaper price and be decribed that way as battery poweredones. so once again ask relevant questions and become informed ,its your hard earned money. so find out what the heck you are buying, see how much time is spend on faraday principle. look at his feedback see if the item he is selling is as described see if his experience is more in selling than buying that rating is every thing/. 98 to 100 percent a good predictor SO IF YOU WANT FAKE OR SHAKE FIND OUT WHAT YOU ARE BUYING ASK RELEVANT QUESTIONS ASK  IF HAS A CAPICITOR OR JUST STRAIGHT POWER CELLS OR LITTLE COIN SHAPED BATTERIES. A TRUE FARADAY LIGHT HAS A CAPICITOR. PEOPLE HAVE INCORPORATED THE WORK SHAKE TO MEAN ALL THREE TYPES NOW THE STRAIGHT FARADAY THE DUAL POWERED AND THE BATTWERY ONES THE FARADAY ARE HARD TO FIND IF THEY DONT SAY ANYHING ABOUT THE FARADAY PRINCIPLE OR PUT MUCH EMPHASIS , CHANCES ARE BATTERY POWERED. NOT MUCH EFFORT FINDING THEM  THEY CAN HAVE BATTERIES BUT NEED THAT CAPACITOR TO BE A FARADAY