This is my second set of wireless alarms that I recently purchased for my home. Most of the alarm units are mounted on my windows. Since my recent burglary I feel a bit more secure having these small alarms armed while we're away, in the hope that the piercing sound they emit will frighten away another would-be burglar.
The alarms I bought today are very similar in looks to the first alarms I installed. They use the same method for setting off the alarm, that is, when two magnets are separated on the unit it will set off the alarm. The batteries are the button-type, and they emit 90 decibels, as do the first set.
Now here's where they differ... The mounting is exactly the same as my other alarms, (double-sided sticky tape), but if you don't line those puppies up juuuust right on these units you'll hear alarms when you don't particularly WANT to hear them!! The directions tell you to line up the arrow (located on one of the pieces that make up the alarm unit), to the notch on the other piece. OK, no problem. Only they don't really mean it. Nope! I lined everything up and then switched on the alarm to test it---whew-boy! I got 90 decibels before I could separate the magnets! So something was obviously wrong. I had to keep sliding the magnets (all the while they're screaming at me), until they fell silent, then try to smack them onto the window frame in that position. After I did that to 4 windows, I tested it again. The alarm went off only AFTER I opened the window, (separating the magnets), just the way it was designed.
These mini-alarms DO work, and they have a nice on and off switch. There's also a setting labeled *chime*, but trust me, it's just another screamin' noise. Nothing "chime-y" about it. The cost for 4 of these alarms was only 9.99. I got them for 4.99 on sale. Could be a reason for that...