The HDMI camera uses 4 pin socket connector to carry video, audio and power over 3-in-one cable. Simply attach the 20 meters extension cable to the socket connector will complete the connection.
The HDMI box has RCA, L audio, R audio, DC5V power and HDMI output. The HDMI box only accept DC5V low voltage power input. Connecting to DC12V power adapter will destroy the HDMI box