Sound Performance 2-way Passive Crossovers With Fantastic Sound For This Herdio Ceiling Speaker.Frequency Response Is 50Hz-20kHz with 89db at 8 Ohms Herdio upgraded tweeters make you to enjoy full range stereo sound . Material and compatibility The Ceiling Speaker Includes Environmentally Friendly ABS Construction And Durable Housings And Grills Can Be Painted To Match Your Home Design.It also can be used with your home amplifier box(Not include amplifier box). Max Power 640 Watts The max power of in ceiling speakers(4 speakers) up to 640 watts. It can achieve wide-ranged sound performance,even in a spacious office you can experience the stereo surround sound of the speakers . Easy To Install And Dimensions The Passive Ceiling Speaker use Flush Mount Design ,Easy In-Wall/In-Ceiling Installation that bring you a clean And Tidy Wall. It Is Very Invisible On The Wall And Total Speaker Diameter: 6.4 Inch(16.2cm) Does Not Take Up Space.