1. Product Name & Standard Official name: Carriage Bolt, also known as Round Head Square Neck Bolt Production standard: DIN 603 / GB/T 14 2. Structural Features It adopts smooth large dome round head. A square neck is designed right below the head. The square neck can be clamped into the square hole of plates to stop the bolt rotating when tightening nuts. The bolt shank contains a smooth unthreaded section and a partial threaded section for nut matching. 3. Material & Strength Grade Main material: Carbon steel, common grade3.6-12.9. Stainless steel A2 / A4 options are available on request. 4. Surface Treatment Standard finish: Blue white zinc plating, offering basic rust and corrosion protection. Other finishes like hot-dip galvanized can be customized. 5. Key Advantages -Smooth rounded head without sharp edges to avoid scratches on operators and materials. -Square neck anti-rotation design simplifies assembly work and improves installation efficiency. -Stable connection performance for medium-load fastening projects. -Rich size range, customized diameters and lengths are acceptable. 6. Application Scenarios Widely used for storage racks, metal fences, guardrails, truck trailers, agricultural machinery, construction frames and general metal-to-wood or metal-to-metal structural connections.