AlKo coupling lock for caravans, horse box, boat trailer etc - Al-Ko universal tow ball coupling lock with integrated keyed safety lock (no padlock needed) - great cost effective anti theft device from Al-Ko Kober. Suitable for all types of caravan, trailer horsebox standard hitches regardless of make. The ball part fits into the tow hitch in exactly the same manner as the tow ball on your car. The purpose of 'blocking' the tow ball hole is to avoid theft by towing away.This product is for standard hitches on caravan, trailer, boat railer, horsebox - This product is NOT suitable for the following AL-KO AK130, AK160, AKS1300, AK2000, AK2500, AKS2004 & AKS3004.