The tow hitch is the important bit - it connects your trailer to your tow bar!
Adjustable height coupling plate to fit between the towbar flange and tow-hitch. Allows the height of the tow hitch above the ground to be adjusted to ensure that the trailer stays level. Particularly useful with vans, pickup trucks, 4x4s or tippers. Fits most 4- or 6-bolt fixed-flange towbars with 90 x 50 bolt pitch (not suitable for use with 2-bolt flanges).