if you apply them correctly. you need one per room (two if it is a big room) they must not be blocked by something. higher works better than lower. lastly what you will find is that you will see more activity from mice the first week or two because it makes them kind of crazy but by 2-3 weeks they get sick of it and leave. get the ones that send out both an audio signal and one on your electric wires and also get the ones that change the frequency now and then so that nothing can get used to it.
description:victor rat traps work very well and kill rats 