I'm skeptical about this product. He says it draws 200 ma and then says it has a backup battery built in.
A backup battery for 200ma for lets say, ten hours would be a lot larger than the case of that unit.
200mA will kill your battery in short order. 30mA is an acceptable parasitic draw. At 50 mA your battery/car stays alive maybe 3-4 weeks (without recharging)