This HAI Dual X-10 Transmitter Kit is intended for use in larger homes to increase X10 signal strength. By using this interface module in addition to the one included with an HAI Controller, X10 signal output is doubled and all electrical circuits receive a clear signal. The kit includes one X10 TW-523 two-way powerline interface and a 25-foot connecting cable. The kit connects to all HAI controllers. Traditional phase couplers are no longer needed. Each TW-523 module will need to plug into different outlets, both of which must be on opposite phases from each other. In a home office, this might already be done where the outlets for the room lights are on the opposite electrical phase from the regular AC outlets.