If you own a Rolex watch, beloved jewelry or a baseball signed by Joe DiMaggio, you should also have a safe. "We all have valuables, even if their value is just sentimental," says Ray Miller, a security consultant in Los Angeles. "When people buy and start using a safe, they often feel they were lucky all those years they didn't have one." Trying to pick from the thousands of home safes on the market can be daunting. Safes, which run from $40 to more than $1,000, are designed to protect their contents from fire, theft or both. Here are some of the most common models: Fire safes: Most people choose these types of safes because they're the cheapest. Companies make the casing of these safes by sandwiching diatomaceous earth between two sheets of metal. The material insulates the valuables and keeps them from turning into ash in a fire. These safes can withstand anything from a half hour of 1,550-degree heat to two hours at 1,850 degrees. Special handling is required to protect film, software, tapes and other electronic media. Companies make small containers that maintain internal temperatures of less than 125 degrees to safeguard this kind of equipment. Fire safes work by releasing steam into the compartment, which keeps everything from burning, which is why it's a good idea to encase any important papers in plastic to protect them from water damage. Burglary safes: Underwriters Laboratories tests safes to gauge their resistance to theft, and then rates them. A "TL-15" rating means it took 15 minutes for a lab technician to break into the safe. Boxes with the highest rating, "TL-30x6," protected their contents for at least 30 minutes on all sides.