-1. connecting,  v4.0 EDR communication protocal could connect 5-8 anti-lost devices at the same time. -2. Powerful function, both-way junction(smartphone anti-lost devices could control each other). -3. Extraordinary working hours, our devices have ability to work about 6 monthes by CR203 button battery power supply, don't need to replace the batteries frequently.   -5. Anti-nuisance function, it can be set to mute for a certain period of time to prevent interruption during work and other important times; -6. Phone control, through the anti-lost device,  users could control the phone shooting function, remote control selfie recording.   Specifications: Communication Protocol: v4.0 EDR Multi Task Management: one smart phone could manage up to 5-8 anti lost devices at the same time. Working Distance: about 20m App Software: Kindelf Battery Efficiency: CR203 button battery, lasting up to three months App Voice: English Compatible system: Apple IOS 5.0 or above / Android 4.3 and 4.0 or above Package includes: 1 x Tracer(Included a CR2032 battery) 1 X English Manual