The Trojan duofit spring operated couplings are the only couplings that comply fully with the New Zealand standard for towball couplings NZS5232:1993 in all respects.  
They are designed to suit 50mm and 1’’ 7/8 tow balls and is rated to maximum GVM of 2500kg, are made from high grade cast iron and coated significantly with corrosion protection for long term maintenance free use.  
A large range of spare parts is also available.