Disconnect the constant power connector of the head unit (deck), car navigation system, etc., and insert the red wire of the capacitor in between, connecting the black wire to the ground. When installed, the sound range will expand and the sound quality will improve due to the power enhancement of the main deck. Many customers repurchase because the low frequencies become more pronounced. It is also effective in reducing noise. It also has versatility for installation on ACC, etc. I am also selling a 47000μF amplifier capacitor in other listings, so please take a look if you'd like. A simple instruction manual is also included. #Capacitor #CarNavigation #CarNavi #Carrozzeria #Rakunavi