1.Aluminium alloy die casting body. Modernize style. 2. Suitable for hollow steel, and wood doors with any kinds of frame, reversible hand installation.3. Adjusting spring power, from size 2 to size 34. According to installed dimension be able to select desirable opening angle5. Universal application for STANDARD, TOP JAMB and PARALLEL arm installation.6. Precise two speed adjusting valve for control door closing smoothly.