TV brake controller compatibility

Find out if the built-in controller is timer based or a proportional controller.  If it is the older-style timer type save your money and don't get that option.  For about $100 you can get a decent Prodigy, which uses the proportional technology.  That matches the braking response from the trailer to what you are doing with the brake pedal - if you hit the brakes in an emergency stop the trailer will immediately give you the same heavy braking, or if you just tap the brakes to slow down in heavy traffic then you'll just get a little braking.  The timer types tend to be "jerky" in slow traffic and never give you all they can in an emergency, because they just slowly give you more brakes up to the limit you've set.  You also have to fiddle with that limit control all the time which isn't true with the proportional type.