If you keep loosing your dog or cat or you just want to know where they go you can use this Petrek 3g advanced GPS pet tracker. Sim card included, 2 different attachments for collars, free phone app, you need a phone to use the tracker. Full specs here: https://pettracking.co.nz/products/petrek-3g-new-2016-model I bought this to use on our Dachshund as she would go hunting in the bush and get tangled up. It worked well but soon after getting it she had an injury and just hasn't really strayed too much from the path so we stopped using it. I bought it a couple of years ago and it's in almost mint condition, everything it came with (including the box) is included, since I haven't used it it has to go. Waterproof, hardy. Good instructions, company is good to deal with.