Replaced my Tyredog system with the TST507 after Tyredog refused to respond to emails, phone calls, etc. My old unit appeared to lock up and I inquired of Tyredog as to how to reset it. They responded and asked for the serial number, etc. After I sent it, they refused to respond to any form of communication, so I junked it and bought the new system. MUCH better system! Works great, easy to set up and program, maintains communication without a booster. Highly recommended!