BOUGHT FOR RV/CAMPER/HOTEL/HOME USE BUT NEVER USED IT. SOLD RV. UNIT MADE BY TANDY CORP. OPERATES ON 9V BATTERY AND IS ADJUSTABLE TO SOUND AND USE. CONTACT SLIPS BETWEEN DOOR FRAME OR UNDER PERSON AND THEN ACTIVATES. PERSONAL BLACK ALARM AND NOISY. THANKS FOR LOOKING  TAKE CARE AND GOD BLESS    FREE SHIPPING(8/10)    fordmanted2b2b