Those are terrible IMO. I've been through several that were tripping false alarms. You can't take the battery out and deal with it later, you have to throw the

Those are terrible IMO. I've been through several that were tripping false alarms. You can't take the battery out and deal with it later, you have to throw the "break irreparably" switch. I prefer the cheap ones that take a 9V battery. You can take them apart and actually dust them.