Seems to work but support is not so good (2009-05-17)
I bought one of these for my garage to keep the mice out in the winter. The loud setting was loud and could be heard clearly a short distance from the garage. It was tolerable though and I never had a complaint from a neighbor. After the winter, I did find some evidence of mice but I have no way of knowing how long it had been there.

One day, a month or so outside of the one year warranty, the unit went silent. I called the support line for B & D, which is also a support line for what seems like half a million other appliances, and was told that it was out of warranty and "nonrepairable", but they would be happy to sell me another at retail price. Since the unit was now worthless, I decided to open it up and see what was inside. I drilled out the rivets (no screws) to get inside and found the inexpensive piezo speaker had stopped working. If I pressed on the cone, it would sound normally. B & D support would not (or could not) sell me with a replacement speaker nor would they give me the spec that would help me find a replacement. In short, if it's out of warranty, we ain't helping you.

The next one I buy will not be a Black and Decker.

A real Noise Maker (2009-03-16)
You should only buy this if you have a serious mouse/rodent problem. Our office building has a severe mice infestation, and nothing else worked. We used several of those un-audible devices but they made no difference. Only this unit set on high keeps the mice away. The sound is VERY audible at this setting. (Even for our neighboring office). We only put it on when we leave the office for the day. Haven't seen any mouse droppings in the morning since then.
I wouldn't recommend this device for home usage. Since even the lowest setting is somewhat audible. But for any tough job... this is the be(a)st!

Pest repellent does the job (2009-03-10)
Before purchasing the Black & Decker pest repeller, I had done quite a bit of research regarding other products currently out in the market. It seemed that this one had a consistently positive review, and I liked what others commented about the product. I purchased the Black & decker for my sister-in-law who had mice problems. The black & decker has two settings: one for rodents and one for insects. It also provides the option of whether you'd prefer a quiet mode, or louder for a bigger room. When I plugged the product into the outlet at her house, I saw a mouse jump at the sound of the machine. I was satisfied that it would work well, and I haven't seen a mouse scamper around her house since. The instructions state that it could take 2 weeks to work efficiently, but I saw quicker results than that. It claims you can't hear it at a quiet setting, but I guess I'm one of the "lucky" ones because I can always hear it when it's on. At it's loudest sound, it's like pulsating pierce. This is VERY annoying and harsh to the ears at a close range. My sister-in-law actually uses this setting at night when she goes to sleep and leaves the little black box in the kitchen. She sleeps on the 3rd floor and the kitchen is in the 2nd floor, so it doesn't disturb her. I have yet to use it for insects, but so far it's a very effective little box. I do recommend the product because it works well.

Didn't work for me! (2009-03-02)
I purchased this unit because I read the good reviews and thought I would give it a try for my problem with squirrels. Each year squirrels nest the in same spot above my living room ceiling in my attic. I had an A/C outlet installed in my attic near the nest (about 10 ft away) and installed this pest repeller. I set the pest switch to insects/rodents and the volume to medium initially for about a week and left it on 24/7. The squirrels were not deterred. I changed the settings to rodents and loud and even installed it on a timer so that it would only come on at night since the loud setting can be heard in the living room and adjacent kitchen. After several weeks of use the squirrels are still there. I wish I could return it as it doesn't work for the squirrels in my attic. I am past the 30 days return period. I guess I can try it on insects and see if it keeps the roaches away that are outside on the back deck!

Pest Repeller (2009-02-16)
The noise is unbearable. I don't know how they can advertise this as something you could use in the house. I have put it outside in my jeep with all the windows rolled up and you can still hear it. It does however seem to be keeping the rats out of my jeep, which is what I bought it for.