Minimum size: 4 inches (18.5mm). Split damping hinge. This new product adopts a 18.5mm ultra-thin shaft structure with a split design. It eliminates the traditional hydraulic oil cavity design and fundamentally solves the industry-wide problems of oil leakage and buffer attenuation failure over long-term use. The product uses a high-strength energy storage spring as the power core. The damping components can be disassembled and replaced separately, significantly reducing the after-sales maintenance cost after the door installation. It can be adapted to various door types such as indoor wooden doors and aluminum frame doors, providing more durable and cost-effective buffer hinge solutions for home decoration projects and foreign trade building materials customers.