upright file box

File boxes are made from a range of materials including polyester fabric, plastic, steel, paper/cardboard, silicone-coated fiberglass (for fire-resistant models), and internal PP (polypropylene) components in some designs.

Some models are marketed as fire-resistant and water-resistant and use a double-layer silicone-coated fiberglass construction. Listings may claim very high temperature tolerance (examples list up to 2000°F); treat these claims cautiously and verify any fire- or water-resistance specifications or certifications with the manufacturer before relying on them.