Scollar Mini's early circuitry was tested at transmitting its GPS coordinates up to 650 meters line of sight as discussed in this blog post (http://scollar.com/scollar-technology-update/). Our latest circuitry grows that signal strength to 800 meters line of sight. Scollar Mini uses an amplified Bluetooth signal, which covers the range of a typical house cat. Buildings and vegetation cause interfere with the signal after about 100 meters. Scollar Mini also uses crowdsourced GPS so anyone with the Scollar app (and partner apps) on their phone will receive and transmit your lost pet's location to your phone via the Scollar cloud service.