The DSP5311 is asurface mount ceiling speakerwith a 70v/100v transformer built in. The 70v/100v transmission is realized in a high-voltage, low-current mode, which makes longer distance transmission and parallel connection of multiple loudspeakers possible.The speaker is made of high-quality engineering plastic, has long-term durability, never out of shape and fading; No roof cutout direct mounting on the ceiling by 4 screws ; 6.5-inch driver unit, with a large and special magnetic circuit ensures strong power.It is an ideal choice for these places, such as schools, gymnasiums, square halls, parks, parking lots, railway stations, airports, villa communities and mall supermarkets, etc.