Safety indocator. If the green cylinder is visible when the trailer is hitched, you know that the coupler is correctly placed on the towbar of the towing vehicle. Waer indicator. An additional indicator at the coupler handle indicates whether the wear limit of the towball of the towing vehicle or of the coupler of the trailer has been reached or not. Ergonomics. The handle complies with the latest regulations and is very flat, so that even with towing vehicles with a low loading edge the tailgate can still be opened easily. MOUNTING: with just 2 screws the old coupler will be dismantled and the now couplee will be mounted.