SU-668 has five circuit board chip protection functions: overshoot protection, overdischarge protection, temperature protection, short circuit protection and voltage protection. Fully manage battery, intelligently allocate fast charging and continuous charging, and extend battery endurance and battery life while cycling charging and discharging. The intelligent control chip is used to control input voltage, and accuracy of input voltage is always maintained to plus or minus 1/1000. Avoid battery life shortening caused by voltage fluctuation. Automatically detect battery voltage, when battery is fully , automatically cut off input voltage to avoid danger caused by overcharge of battery. The receiving distance of partition wall is 50-100m. Open receiving distance is 1500 meters. Tips: The distance is too far to reach additive signal intensifier. Thanks for choosing queuing wireless calling system. It adopts wireless technology with millions of different learning codes. The system includes 999-channel call keyboard and portable buzzer& vibration receivers. Each receiveris rechargeable and And it has a number. In standby status, Superposition of charging. while client places an order, he(she) be dispatched one receiver with a number, when order is ready, the keypad to call number, the client through buzzer/vibration/LED indications. The queuing system greatly improve work ef ciency and avoid client waiting in a long queue. It is widely used in fast food restaurant, dessert shop, Coffee house, Pizza shops, auto 4S shop or other queue occasions. Why you use? Minimize crowds in waiting Reduce staff chaos & improve amdience Notify people faster Improve work efficiency Enhances restaurant's inage 999 channels keypad call buttons Superposition charging Portable rechargeable vibration & buzzer receiver storage memory avoiding data lost High receive sensitivity Self testing while power on Beautiful and fashionable designing Working voltage: DC12V power adapter, DC5V power adapte Working frequency: 433.92MHz Working current:20030m A Standby current: 6010mA Encoder: Learning code (AM) Dimensions:150 x 113 x 72mm, 20 x 80 x 30mm Qperating temperature:-10C-60C Transmitter distance: more than 500 meters(Undisturbed open space) Plug Type:US Plug,it applies to Canada, India,Mexico, Thailand, the , the Philippines,Taiwan and so on. Voltage:AC100-240V Color: As Shown Material: plastic Package Contents: 1 * calling machine buutton 10 * receiving cards Only above package content, other products are not included. Note: Light reflection and different displays may cause color of item in picture a little different from real thing. The measurement allowed error is +/- 1-3cm.