Fits most 50mm Avonride cast coupling heads including 575003, 575004, 575005, 575008 Suitable for many Ifor Williams trailers and horseboxes, plus Nugent trailers The strong and robust high visibility yellow hardened steel casing with anti-saw features covers the fixing bolts of the hitch to protect it from being stolen Approved by Secured by Design - tested to the high standards set by Secured by Design and meet Police Preferred Specification Approved to Sold Secure Gold standard for trailers - independently tested by the Master Locksmith Association Provides security for a car and trailer when they are parked coupled together e.g. motorway services (NOTE – for safety reasons this product is not recommended for use while towing) Allows use of Avonride integral lock for extra level of security Unique high security patented locking system High security pick-free locks have thousands of possible key combinations and are supplied with 3 keys, plus a key identity tag Water and corrosion proof