1. The spring has high strength and durability, and the opening angle is 80°. 2. Robust and durable stainless steel hinge, rust-proof, corrosion-free, and long-lasting. Invisible design, simple and practical. 3. Each package contains one left and one right spring hinge, without screws. 4. To support upward lifting equipment, it is suitable for folding beds, folding sofas, folding sofas, cabinet doors with lift-up doors, etc.