DOOR KNOCKER SIGNALER light flashes when someone knock at the door. Great for privacy and portable use. It can be used in one room apt., dorm, office, hotel... anywhere - great for travel. Easily hung over the top of any door. (bracket included) Battery operated. (9V battery is included) Battery Low Indicator. THIS ITEM IS DROP SHIPPED DIRECTLY FROM THE MANUFACTURER AND IS A 10-15 DAY DELIVERY. THIS IS A SPECIAL ORDER ITEM AND IS NOT RETURNABLE. (Unless the item is defective.)