The 76.2 × 12.7 mm mesh with 4 mm wire is the recognised standard for perimeters that must defeat climbing. Here is what the numbers mean and where to specify them.
358 = 76.2 × 12.7 mm aperture, 4 mm wire. The shallow 12.7 mm vertical gap denies finger and foot purchase; the 4 mm wire resists bolt-cutters. Specify 358 where security fencing must stop climbing — utilities, data centres, prisons — and finish it with hot-dip galvanizing to EN ISO 1461 / ASTM A123. It is a delay layer, paired with detection, not a standalone wall.
The shortest answer: 358 is a welded mesh with a 76.2 × 12.7 mm opening and 4 mm wire — sized so humans cannot climb it and hand tools cannot quickly cut it.
"358" is the specification written in imperial shorthand: 3 inches × 0.5 inch × 8 gauge. Translated, that is a 76.2 mm horizontal aperture, a 12.7 mm vertical aperture and 4 mm wire. The rectangle is wide but shallow on purpose — and that single geometry is what makes the fence anti-climb. Zhaobang supplies 358 as part of its Custom Metal Fencing range, built to drawing with matched posts and rails.
Geometry, not thickness, is the defence.
| Parameter | Value | Security effect |
|---|---|---|
| Horizontal aperture | 76.2 mm (3 in) | Open sightlines, CCTV see-through |
| Vertical aperture | 12.7 mm (0.5 in) | Too narrow for toe/finger hold |
| Wire diameter | 4 mm (8 gauge) | Resists bolt-cutter shear |
| Typical height | 2.0 – 3.0 m+ (custom) | Scales with risk; posts sized to match |
Standard welded fence openings run 50×50–200×200 mm; 358 is the deliberate exception, optimised for anti-climb performance rather than maximum open area.
Two threats, one geometry.
Climbing. A climber needs a toe hold and a hand hold. The 12.7 mm vertical gap is too small for adult fingers and too shallow for a boot edge, so the fence offers no continuous purchase. Combined with a flat, rigid plane, 358 removes the step-and-reach rhythm that makes ordinary mesh climbable.
Cutting. The 4 mm wire is beyond the bite of a standard hand-held bolt-cutter, and the welded intersections force a grinder to work every wire individually. That is delay, not impossibility — so 358 belongs inside a layered security fencing system with sensors and cameras.
358 earns its cost where the perimeter is the last line.
Specify 358 for utilities, substations, data centres, prisons, airports and chemical sites — anywhere a breach carries real consequence. For a general warehouse or school boundary, a 50×50 mm welded panel (see the welded wire fence types comparison) is usually enough and cheaper. Use 358 when climbing is the defined threat, not merely a possibility, and add detection so the delay the mesh creates becomes response time.
Finish the system, not just the mesh.
Finish mesh and posts with hot-dip galvanizing to EN ISO 1461, or a duplex (galvanized plus powder) coat for coastal or branded frontages where ASTM A123 is the equivalent zinc reference. Size posts to height — thicker-wall sections for 3.0 m and taller — and clamp panels so the rigid plane stays flat. Where regulation demands it, add a razor-concertina topping on outrigger arms. Send a layout and the fencing specifications page decision tree sizes the rest.
The name is the specification in imperial units: 3 inches by 0.5 inch by 8 gauge. Converted, that is a 76.2 mm horizontal aperture, a 12.7 mm vertical aperture and 4 mm wire (8 gauge). The wide-but-shallow rectangle is deliberate — the 12.7 mm vertical gap is too narrow for adult fingers to grip, so there is no purchase for climbing, while the 4 mm wire is too thick for a hand-held bolt-cutter to shear in one bite. The numbers are the reason the fence works, not just a product code.
358 mesh is delay-rated, not tool-proof. The tight aperture defeats hands and feet, and the 4 mm welds resist casual cutting, so most opportunistic intruders give up. A prepared attacker with an angle grinder can still cut it, which is why high-security sites pair 358 with intrusion detection, CCTV and topped barriers such as razor concertina. Treat 358 as the physical layer of a layered security fence — it buys the response time that sensors and guards need, rather than standing alone as the only defence.
Finish 358 mesh and posts with hot-dip galvanizing to EN ISO 1461, or a galvanized-plus-powder duplex system for coastal or branded sites; ASTM A123 is the equivalent reference for the zinc coating. Posts are sized to height — thicker-wall sections for 3.0 m and taller runs — and panels clamp to them so the rigid plane stays flat. Because Zhaobang builds to drawing, post structure, rail size and mesh opening are matched per project rather than pulled from a fixed catalogue, keeping the whole perimeter consistent.
Yes. The 76.2 mm horizontal aperture keeps the fence open enough for clear sightlines and CCTV coverage, so guards and cameras see through it despite the anti-climb density. That is why 358 is common around utilities, data centres and prisons where both detection and deterrence are required. If you need a solid visual screen as well, add a separate anti-climb topping or a sight-obscuring panel above the mesh rather than closing the 358 grid, which would defeat its visibility advantage.