... doll which people take with keys is infrom people alarm if having the thief stolen your product2.the concealment ... ,because if some people shake your something such as car ,box ,home door ,,the other doll speak can ... you4.the batter use 12V23A,no need change the car wire ,fit any product ,inform distanct is more ... than 500-1kmso if you drive your car go shopping ,dont worry ,because the 500-1km ...