If we knew we were only going to be towing a single vehicle, we'd have probably purchased a permanently installed braking system. However, we knew we'd be towing different vehicles so we opted for a portable system that we can move from car to car. We bought the RVi Brake 2, which is an updated version of the Brake Buddy type design. The RVi has a few new features and true proportional braking. It installs in less than a minute and it's only about 1/3 as tall as the BB, so I can store it in a smaller area, which is nice.
Kev