Trailers that do not exceed 3.5 tonnes ATM must have a quick release coupling which is designed to be engaged and disengaged without the use of tools. It must be of a positive locking type with provision for a second independent device. The locking must be readily verifiable by visual inspection. 
Fixed none brake coupling normally suited to a 50mm Australian Standard tow ball, where either no brakes fitted or the brake system does not require activation from a sliding or overrun coupling
 
2 Holes 101.6mm
Suit for 50mm Tow Ball
2000kg Maximum Rating
Adjustable Tow Ball Anti Rattle Screw
Quick Release Lockable Safety Trigger
Safety R Pin for Secure Lock