What is the trailer coupler?
A coupler is a mechanism that is bolted or welded onto the end of a trailer tongue. It fits securely over - and pivots on - the tow vehicle hitch ball.
Should the ball hitch and coupler be the same size?
Most trailers list hitch ball size (diameter) and maximum towing capacity on the tongue, coupler, or frame. Any hitch ball used to tow the trailer should have the same diameter and a maximum capacity the same or greater than that listed. Common hitch ball diameters are: 1-7/8", 2", and 2-5/16".