Underwriters Laboratories (UL) certifies that the safes have been independently tested to meet their fire protection criteria.
UL-350 Fire Endurance Test (which these safes have) performs these tests:
Raise the exterior heat to 1200°F within 8 minutes.
Maintained 1200°F to 1700&def;F for 1-hour test, or 1200°F to 1850&def;F for 2-hour test
Interior of the safe stayed below 350°F for the entire time.
Many manufacturers will say they have tested their fire safes but without a UL label you have to trust their rating. UL rated safes give you the peace of mind that the safe has been independently tested to work as advertised.
Paper burns at 450°F, DVD's, USB drives, etc MAY survive at 350 degrees but you may want to consider a UL-150 Data Safe if this is your primary concern. They start at about $500 and must be special ordered.