BrakeSmart Intelligent Trailer BrakesIt is a bit on the expensive side, but about the best you can get. It uses a pressure sensor on the vehicles braking system to apply the correct amount of braking power. Completely adjustable for initial setting and proportion rate. Have towed a variety of trailer yet seldom need to adjust it.
With a properly balanced trailer, there will never be a need to manually activate it. During a panic stop, the pressure in the vehicle system will increase the trailer brakes.
Tried the prodigy and tekonsha before finally finding this unit. Have no regrets about spending the money on the unit.