Size:Transmitter: 7*3.5*2cm/2.76*1.38*0.79"Receiver: 8.5*5*2cm/3.35*1.97*0.79"Operation:After the batteries are installed, turn the receiver switch to the selection position (each press for a ringtone, if you want to fix a music, the switch to the sound position (music symbol) Can be fixed. Features:Wireless, easy installation.High-frequency vibration body, penetrating ability,up to 70-110 meters remote control in the open air.4 kinds of volume adjustable, the sound is loud and clear.36 music ringtones optional,while the music is on, the LED flashes simultaneously.Perfect for big and high floor houses, offices, factories, hotels, etc.Specifications:Model: 513EMaterial:ABS(Acrylonitrile Butadiene Styrene plastic)Color: Black&BlueFrequency: 315 HzVoltage:3VPower consumption: 0.5 (W)