The DSAL-2 125db door stop burglar alarm is more than just a door alarm, it also stops the door from being opened. This is the only door alarm I know of that gives you this added measure of safety. If someone tries to force the door, the pressure sensor in the unit is triggered and the 125db alarm will sound. The alarm turns off when the pressure is released from door stop plate. Also works as a door jam. Uses one 9-volt battery. Shipping is FREE on orders of $50 or more ($6.50 on smaller orders). To purchase the DSAL-2 simply click on the link to my secure website below.