A weight distribution system will include a receiver hitch on the tow vehicle, removable receiver hitch with your ball on it, and a spring bar assembly. Most of the weight distribution hitch systems and spring bar assemblies are going to mount to the receiver hitch on your tow vehicle. Instead of putting all your tongue weight on the receive hitch, the weight distribution system will apply leverage between the trailer and tow vehicle. By applying the leverage this way it will transfer to tongue weight to the rear of the trailer and the front of the tow vehicle. When you transfer to the tongue weight away from the receiver hitch is allows you to tow a heavier trailer. It will also assist you in better brake and steering control and level out the trailer with the tow vehicle.
So when do you need a weight distribution system for you towing setup. Here are a few suggestions below that may help you decide if you are a candidate.
1) Your tow vehicle headlights point upward
2) It is difficult to stop or steer your vehicle
3) You are getting trailer sway
4) The tow vehicle is sagging in the rear when the trailer is on
5) Your gross trailer weight is more than 50 percent of your tow vehicle
In order to use a weight distribution hitch your trailer must be rated for it. If there is not a rating listed on the trailer for a weight distribution system you will be unable to use one.