This is an inertia type brake system for flat towing a vehicle. I used it for 2 years when I was towing a jeep wrangler until I sold the jeep. It worked flawlessly and safely let me travel through the Rockies many times. As I sold the jeep, part of the kit went with it, so I have purchased a new “extra vehicle kit” to make it exactly like the full, new kits you see on ebay, but for much less investment.