SXOPA Xiang gull brand suitable schools, offices, external amplifier bad place, you can monitor the video and computer connection, there is no way you can achieve the project take place amplifier, bass good, 12V and 220V can be selected. Rated power: 10-20W Unit Size: 6 inches Frequency: 45-20KHz voltage: 220V Dimensions: φ210 hole size: φ180 Material: ABS plastic. SXOPA Xiang gull brand suitable school, built-in amplifier, high-fidelity wireless audio receiver module. Direct connection 220V power use, no wiring. Wireless Frequency: 798MHZ, wireless distance: 100 m radius Speaker power: 10W, size: 228 * 75mm can send 200 receives a sound without delay. Hole size 175MM active ceiling speakers