When selecting a steel file rack, prioritize Cold-Rolled Steel (SPCC) over hot-rolled steel, as it offers superior strength and a smoother finish. Ensure the thickness is at least 0.6mm to 0.8mm for standard office use to prevent warping under heavy paper loads. For the surface, look for Electrostatic Powder Coating rather than traditional paint; this provides scratch resistance, anti-corrosion properties, and environmental compliance (Lead-free), ensuring the rack withstands high-traffic office environments.