This is a security alarm that sounds when it detects the opening or closing of a window. Please refer to the package photo for detailed product features. I purchased this about 7 or 8 years ago and have been storing it at home. Therefore, I am offering it at a low price. Although unopened, the package shows signs of aging. Batteries are not included. We recommend purchasing new batteries separately (Lithium battery CR2032 x 2). I have not tested the operation as it is unopened. Although unused and unopened, this item has been stored at home for a long time, so please understand this before purchasing.