The Adastra 4*EC36V+US60 package includes 4 ceiling speakers 100V and a 60W power amplifier, ideal for commercial audio systems. The US series amplifiers are designed for easy installation in racks or walls and accept 100V speaker power. The connection is simple, just connect the 100V input of the amplifier to the last speaker in the series. You can add more speakers, provided their total power is below 90% of the amplifier's maximum output power. - US series 100V power amplifier - 4 mini ceiling speakers EC36V - 50-meter speaker cable - 0.5 m double RCA connection cable from mixer output to amplifier Note: Use terminal blocks for extending the speaker cable. Avoid direct connection of + and -