A safe is a container where people can put important things to protect them from fire, theft, or both. A safe is usually a box-shaped container with a lock. Safes that are designed to protect things from just fire may not have a lock or may have only a simple lock or padlock hasp. It is usually heavy and made of a strong substance such as steel. It is designed to be very hard to open with crowbars, hammers, drills, lock picks, and other tools. Safes are available in many different security levels. These range from those designed to protect from common burglars to those designed to protect from professional thieves and spies. Fire ratings are usually based on how long the safe can be in a common structure fire before the inside of the safe reaches 175 degrees Celsius. This is the temperature at which paper and wood are destroyed. The fire rating usually ranges from 15 minutes up to 3 hours. Some safes are also waterproof, which both protects the contents from flood and prevents the contents from getting wet when a fire is put out by firefighters. A large safe that is part of a building is called a vault. Vaults have usually one or more rooms.