The Garmin GTU 10 is a small, portable and waterproof gadget that transmits its location and creates a digital breadcrumb trail. It\'s aimed at campers, hikers, hunters and other outdoor enthusiasts as well as people who want to keep track of footloose pets, children, parents or Owners can create up to 10 geofences — virtual boundaries that might incorporate a backyard or school campus. When the device enters or exits a geofenced area, Garmin can send an email or text-message notification to a designated mobile phone or other receiver, such as a home security system or digital photo frame. The GTU 10 costs about $200 at sports-equipment stores and AT&T mobile phone stores. After the first year of free tracking, the service costs $49 a year.