For rack decking mesh, wire diameter means the diameter of the load-bearing wire, and mesh opening means the center-to-center spacing of adjacent wires. Together they determine the mesh's load capacity and spill control; select by goods weight and smallest part size, not just by the quote.
Common wire diameters are 3.8 mm, 4.5 mm, 5 mm and 6 mm. Light-duty mesh (100–200 kg per layer) uses 3.8–4.5 mm; medium duty (200–500 kg) uses 4.5–5 mm; heavy duty (500 kg+) uses 6 mm with dense mesh or reinforcing ribs. A thicker wire raises load capacity clearly, but self-weight and cost rise in step.
Common mesh openings are 50×50 mm, 50×100 mm and 100×100 mm. For small parts, bagged material, bolts and nuts choose the dense 50×50 mm; for turnover bins, palletized goods and large items choose 50×100 mm or larger. A mesh that's too large leaks small parts; too small uses more material, costs more and ventilates poorly.
Practical combos: medium racks commonly use 4.5 mm wire with 50×100 mm mesh; heavy racks use 6 mm wire with 50×50 mm mesh plus reinforcing ribs. Tongnuo can match wire-and-mesh combos by per-layer load and the goods' smallest part, avoiding over- or under-design.
On acceptance, measure wire diameter with vernier calipers and mesh opening with a steel ruler, checking against the contract; then run a uniform-load test, pressing to 1.2 times the rated load; mesh deflection must not exceed 1/200 of the span to pass.