Alko hitch head lock replacement trailer security hitch lock barrel lock. Will fit the Alko AK301 and AK351 hitches, fitted on many braked trailers including Boat trailers and most braked Brian James Trailers. Can be locked when hitched or unhitched to the towing vehicle and prevents the towing handle being raised to couple/uncouple a tow ball. By using an SAS Dummy Towball with the lock when unhitched it will prevent coupling up with a modified towball. Supplied with 2 security keys.