Review on Dive into Silence: Dogtek Sonic Bird House Bark Control Outdoor/Indoor - Enhanced Version by Nicole Shrestha

LOVE it, it works. At first I put it in my yard, away from the neighbor's constantly barking dogs, and it only worked as if and when it was aimed (swinging and moving) directly at the dog. It also only worked on a large dog, not a small yapping one. I then planted a second (I was desperate) on my neighbor's tree which is within 10 feet of the balcony where the two dogs are constantly barking. I also strengthened him enough that he never strayed from the dogs. This time it worked out great for both of them. They will bark once and look at it, then whine and stop. Love it! But you have to be close and direct. I'm not sure 50 feet is absolutely accurate.