Semi-automatic twistlock is placed between containers in a s stack. It is applied to lock into corner casting above and below. Semi-automatic twistlocks can be locked automatically when the containers are set in place, but must be manually unlocked. The closed hot-dip galvanized housing protects the twistlock’s internal mechanism from wear and tear at sea and during cargo handling operations, guaranteeing durable performance and trouble-free operation throughout its lifetime.