A shelf frame for a rack of shelves includes an elongated body; a ledge extending perpendicularly from a bottom edge of the elongated body, the ledge having a width equal to a height of the elongated body; an elongated enhancement disposed along a top edge of the elongated body, the enhancement being bent toward the ledge; two upright extensions disposed at two ends of the elongated body respectively; and a plurality of fasteners disposed in each of the two upright extensions. The two upright extensions and the elongated body are on the same plane. Each of the two upright extensions has a length equal to twice of the height of the elongated body.