The gauge of steel relates to the thickness of the steel. The smaller the number, the thicker the steel and the larger the number, the thinner the steel. Our safes usually range between 7 gauge and 14 gauge steel, with 7 gauge being the thickest steel. The gauge is very important for a safe. The thicker the steel, the harder it is for a thief to drill through and the longer it takes for a fire’s heat to penetrate to the interior of the safe.