The Parkit360 Smart Brake Control operates automatically when you plug your trailer's wire harness into the Parkit360 trailer plug receptacle.
With a trailer equipped with electric brakes (Usually RV trailers) the brakes are applied when you let go of the Parkit360 forward and reverse controls.
With a trailer equipped with surge (Usually boat trailers) (see video below explains surge brakes) brakes the trailer brakes are released as soon as the plug is connected. Basically the surge brake option is a lockout so that the brakes don't lock up while you are trying to push the trailer backwards.
Parkit360 Trailer Dolly sold separately
This part is non refundable