If you lose your dog, the odds that he will still be close enough for a bell to get you to him is remotely small. They are very annoying, talk about a great way to destroy the sounds of nature. I use a leash, backed up with a tag on the collar and the final most important step, microchip. I can not even guess how many lost dogs I have seen or heard of over the years. In most cases, its off leash hiking dogs who ran into something that caused them to run or they just wandered off. Frankly and this is just my opinion. I cant fathom how people take the chance to let their dogs off leash while hiking.