Frienda LED Ultrasonic Dog Trainer Device 3 in 1 Stop Barking Stop Bark Handheld Dog Training Device (Yellow)

I was looking for something to deter my dog from some annoying behavior, and I didn’t want to spend $20 for a can of air. The price was right and it sounded plausible, if not completely promising. I thought it was worth a try.Forget the instructions, they are written by someone whose first language is something other than English, and while not totally informative, are highly amusing. (“Attention: Do not irritate dog very often when they already stay quiet or in noisy environment. When the dog bark or attempt to attack you, the effect of ultrasonic training device is best.”–I’m not sure how you get the dog to attack you, but you might want to try it with barking first.)It requires a 9 volt battery, and will double as a flashlight. I’m not exactly sure why, but it’s handy if you’re stuck in the dark I suppose. The device is bright yellow and has 3 settings, which are difficult to see because they are molded into the plastic. The top one is just the flashlight, the middle one is a picture of a dog standing/dancing on it’s hind legs. Maybe that’s for training? The third setting is a dog lying on it’s side, what I call ‘dead dog’ mode. I use that one when I mean business. And, oddly, it seems to work. I started in ‘standing/dancing dog’ mode and my dog definitely reacts to it, it gets his attention and he’ll usually stop what he’s doing, at least temporarily. He may return to the behavior if it’s something he truly enjoys, like playing tug of war with the leash, and I’ll hit it again. That’s usually enough. If he’s being especially stubborn, or if I think the behavior might hurt someone (jumping on them in greeting), I’ll resort to ‘dead dog mode’ and that will usually do the trick. He stops. I’ve even used it at the dog park when a group of dogs were getting out of hand, and after hitting the ‘dead dog mode’ button, they stopped. I’ve even tried it, in ‘standing dog’ mode when some dog is barking at us when we walk by. It stopped. Now, most of the time, just seeing me pull the device out of my pocket is enough to get my dog to stop whatever annoying thing he’s doing. And I threaten him with ‘dead dog’ mode if he doesn’t straighten up.The bottom line is that this crazy thing actually works, at least on my stubborn boy. I try to use it sparingly because I don’t want to quash his joy, just keep him from doing things that can cause damage or injury. (the leash pulling is hell on my elbow!) I don’t know how long it lasts, but I’ve not drained a battery yet. And the flashlight is useful as it lights every time you push the button, so the dog thinks he may get blasted when he sees the light and that’s enough to stop the behavior. I can’t claim it works every time, but it works enough of the time for it to be worthwhile. If it works on coyotes, I’ll let you know.Addendum: This morning I had an encounter with a coyote as I was walking my dog, the coyote was in the bushes about 50 yards away, with eyes on me, another dog walker, and our dogs. I pulled out my trusty Frienda zapper, pointed it at the coyote set on ‘dead dog’ mode, pushed the button and the coyote bolted immediately. So, I think I’ll up my review to 5 stars. Anything that deters a coyote is my best friend.