Cruisemaster D045 Plus Security Lock SystemEnsure the safety of your camper or caravan when you're not there with Cruisemaster's own DO45 Security Lock. DO45Plus Security Lock. The Cruisemaster DO45Plus Security Lock assembly consists of a dummy pin, two keys and lock chamber with dust cover. How does it work? The dummy pin is to be inserted through the top of the DO45Plus locking mechanism with the tip of the pin protruding out at the bottom. The lock is then fitted to the protruding end of