It's not made of metal but the Latitude 5400 is a durable machine capable of withstanding extreme conditions. The laptop passed 17 MIL-STD 810G tests, which means it can endure high temperatures, exposure to sand and dust, and multiple drops, among other conditions that would kill a regular laptop.
A durable exterior will protect your important files from yourself, while the Latitude 5400's security features will defend against others.