For through transom bolted engine installations. As two stroke outboard motors become rarer and new heavier four stroke outboard engines take their place, many owners of 8hp engines and above sensibly choose to bolt the engine through the transom in a semi-permanent installation.Our tried and tested bolt locks are intended for use with through bolts that are coach, countersunk or stepped so that, should a thief attack the head of the bolt and remove it, they will be unable to hammer the bolt shank through the existing hole.We manufacture three bolt lock models for through transom bolted outboard engines. Each has a 13mm diameter hole in the body unit. A brass reducing T-sectioned bush is available to reduce the hole to 10mm.Pacific Bolt LockThe Pacific Bolt Lock is our original lock that uses the same high security locking head as the Volcano. Includes lock dust cover.