A booster bag is a handmade bag used to shoplift, typically from retail stores, libraries, and any other location employing security detectors to deter theft.The booster bag can be an ordinary shopping bag, backpack, pocketed garment, or other inconspicuous container whose inside is lined with a special material, typically multiple layers of aluminium foil. Booster bags have been used by professional shoplifters for several years. Once a bag has been successfully tested, a shoplifter can steal dozens of items with very little effort.