straight-way intercom system outerdoor station : CS-200Z-1 indoor phone : CS-300F-1or CS-300F-2 fittings : Power ( CS-12V ) Module( CS-YMQ ) 1 outerdoor station + 1 indoor phone = 1 set Functions: 1)Applies to 2x7 or 3x7 building 2)Indoor station adopt 2-pair cable. Any fault of extension won''t impact on normal operations of the system 3)Outdoor station is subject to intelligent control by microcomputer chip ensures a stable running 4)The talks through indoor unit are kept secret Specification: 1) Power Supply: DC12V 2) Power Consumption:100MA/300MA 3) Chime:dingdong chime more than 80dB 4) Distortion: less than 8% 5) Audio SNR: more than 55dB 7) Operation temperature:-10oC~+ 55oC 8)Installation: embedded