Cruisemaster D035 V1 Security Lock SystemEnsure the safety of your camper or caravan when you're not there with Cruisemaster's own DO35 Security Lock. Gen. 2 DO35 Security Lock. The Cruisemaster DO35 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 into the DO35 universal joint from the top end and the tip of the pin will protrude out at the bottom. The lock is then fitted to the protruding end of the