I use the TAGG system. We have a dog and cat, and both have TAGG trackers. TAGG also allows you to download the TAGG app and you are able to track the TAGG tracker directly from the app. I had looked into trackers and I choose this one due to no GSM cell service in my area. The TAGG tracker use's CDMA cell service. Their service map looks very similar to the Verizon service map. I was able to find a brand new tracker for $60, which included 3 months of service for free. After that service can be 9.99 per month on a monthly basis, or 7.95 a month if you buy the full year. The system comes with collar attachments which fit pretty good to the landing skid of the bird. The attachments allow you to simply attache and detach the TAGG tracker when you wish. So most of the time the TAGG is out dog, but when i go flying i grab it off her collar and attach it to the other attachment i have on the landing skid of the bird.