The AL-KO Non-Braked Duofit Lever Trailer Coupling is designed to fit 50mm and 1 7/8" towballs easily, without the need to swap the handle. No confusion with the respective towball sizes! The duofit coupling negates the need for you to change over the handle. The coupling simply fits to the size of the towball automatically.
 
4 bolt holes 90mm x 36mm centres
Low profile
Automatic easy locking