20-mesh fine wire mesh with 1 mm openings. This mesh size allows optimal air flow through ventilation openings while forming a solid barrier. Helps keep unwanted guests out and prevents entry into your home. Material: woven stainless steel wire fabric; acid- and alkali-resistant; high strength, tensile strength, toughness, and wear resistance; long service life. Product features: smooth, durable surface with a precise mesh pattern; rust resistant and corrosion resistant; sturdy structure resists deformation; does not rust and does not leave rust stains on bricks or wood; ideal for vent bricks. Wide application: suitable for vent openings in doors, windows, vent bricks, kitchens, ventilation openings, and bathrooms; also usable in gardens or yard drainage to keep leaves from clogging pipes; easy maintenance and easy to use.