The WA121 is a 3W ceiling speaker with 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 built-in 4.5” speaker driver is designed of wide frequency response 100Hz-16KHz, It is made of high quality engineering plastic, which ensures long-term durability, and will never be out of shape or fading; Spring clip clamp makes the easy and secure installation;  Driver surround excellent damping, long life, clear and sonorous sound.
It is an ideal choice for industrial and commercial applications in hotel, school, office and factory where background music and paging is needed.