1. 8000 series has aluminum die casting crust & aluminum crust total 2 kinds 2. Closing & latching speed can be adjusted Has the buffer function after door 65degree opened, and the function can be adjustable. 3. Has delay function from 180-65degree door closed, and the function can also be adjustable 4. Has an aluminum crust, door closer item 812-4 is advanced structure, stable performance. The speed valve locates over or below the door closer body to ensure it has a convenient & comfortable adjustment & operation circumstance. 5. Closing force can be adjusted for this 812-2 item. 6. Vertical, parallel or sliding rail installation style can be selected