Some quick couplings and simple pipe fittings achieve "external snap" connection through external snap and lock structures, without the need for threads. By pressing or pulling the external snap, they can be quickly installed and disassembled. Quick couplings in hydraulic systems (such as quick-change couplings for agricultural machinery hydraulic pipelines) often adopt this "external snap" mechanical locking structure.

External fastening refers to a wide range of components and systems used to securely join or fix parts on the exterior of structures, equipment, or products. These fastening solutions are widely applied in construction, machinery, automotive, energy, and industrial manufacturing industries, where strength, stability, and long-term reliability are essential. Typical external fasteners include bolts, nuts, screws, anchors, clamps, and brackets, all designed to withstand mechanical loads and environmental exposure.

External fastening systems are commonly manufactured from carbon steel, stainless steel, alloy steel, or aluminum, and may be treated with surface finishes such as galvanizing, zinc plating, anodizing, or coating to enhance corrosion resistance. Properly selected external fasteners ensure structural integrity, resist vibration and fatigue, and maintain performance under varying temperatures and weather conditions. With standardized dimensions and customizable options, external fastening provides safe, efficient, and dependable solutions for permanent or removable connections.