A burglary and fire-resistant safe is designed to protect the contents from very high temperature as well as actual fire. They are usually rated by the time they can withstand the extreme temperatures, while not exceeding an internal temperature of 350°F (177°C). Most safes are rated between 30 minutes and 4 hours, the most common being 1 hour. A burglary and fire-resistant safe is also designed to protect against burglary. This is measured in their resistance to the type of tools used and the length of time. The most common, is a RSC (Residential Security Container).