Wireless transmission, easy installation, ready to use after delivery.Adopt waterproof design to avoid corrosion from tea, oil and water during work.Built-in 300mAh large-capacity lithium battery, capable of 37 hours of standby.Super resistant and anti-fall. All internal circuits are reinforced and more stable against drops.Can be used with 16 receivers, no need to worry about insufficient occasions.Adaptive power supply: DC 12V/1ACharging current: 20-50mAStandby time: 200 hoursNumber of code pairing: 998Prompt mode: buzzer/vibration/lightModulation mode: AM OOKWorking frequency: 433.92MHZMenu option:set prompt time:set buzzer speedSet base ID/set extension number:set switch vibrationTransmission distance: 800 meters in open spaceVoltage:AC220VPlug Type:EU Plug,it applies to Indonesia, Germany, France, Spain, Italy and so onNote:Due to different production batches, there may be slight differences in products. Colour:BlackMaterial:ABSPackage Contents:1 x Wireless Calling System16 x ReceiverOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.