I feel after having this for a few months I can officially write a review.First, I got this amazing product for my cat. I moved in with my boyfriend into a house at the beginning of the year and he has two medium sized dogs who use the dog door to go potty. I also brought with me my two indoor only cats, who were about 6 years upon move in. We knew our biggest challenge was my indoor cats and the dog door. I knew I had to give in and let them be outdoor during the day when we were not home and bring them in at night where they could be locked in our room for bedtime with us, which would keep them safe from predators and allow the dogs to still use the dog door to go potty through the night. Everything was going great until my cats got out a little early one morning, at 5am but before the sun was fully up. And, it was the last time we’ve seen my girl cat. Devastated by the loss of my cat who was practically my child I sought after something that would allow me to find my other in case of him getting out or anything of sorts. I wanted to know where he was going and when. Insert the whistle....I was skeptical at first, in fact, I almost sent it back after the first week. I realized my cat stays mostly within range of our WiFi, so even if we can’t see him the whistle can’t find him if he’s close enough for WiFi connection. So I thought it wouldn’t work for us. But, luckily he generally comes to my whistle and voice if he’s that close. We decided to really stick it out and give it a try.He has accidentally got out a handful of times at night and usually out of range of WiFi. And, the whistle has done its job every night including tonight. If it wasn’t for the whistle my cat probably wouldn’t be home safe with tin 10 minutes of realizing he’s gone every single night he’s got out. The whistle alerts me when he goes out of range shows me right where he is ( our house is back against a trail that is dirt and people walk in but it takes you into trees) and it shows where I am so I know when I’m getting close. The minute I get a text he’s out of his allowed area I am able to turn on the fast flash ( I almost didn’t get this feature, if you’re getting it for a cat you NEED this feature) and I can spot the flash from super far away. And, we’ve done this so many times that when we get close to him he’s usually starting to run back home because he sees the flash. We believe he knows that means come home or we’re coming for him.Because, he’s in WiFi range for a majority of the day the battery last a week if not more before needing to be charge. ALWAYS fully charge it especially if you’re gone for a week. I made this mistake when we went on a week vacation to another state. We locked him in our room the entire trip so he couldn’t go outside at all as we wouldn’t be home and I didn’t want the cat sitter to have the responsibility of ensuring he was inside before sunset every evening. The last few days we were out of state I got alerts he was super far from home and the cat sitter who lives down the street had to come over and make sure he was here, and he was. The battery was just so low it started glitching. So that was a user error not a whistle error and it’s just a PSA for anyone who purchases it.I am so obsessed with this product and I cannot speak more highly of it!