Material: Made of environmental aluminum alloy casting body, with built-in anti-external force device offer a protection for the door, door frame and door closer, ensuring durable in use Adjustable: Two independent valves to control the closing speed and the latching speed, Self regulate the mechanism to meet your needs Back Check Function: Will slow down after the door is opening to 60 degree, prevent the door lock and door product damage or wall collision caused by the door opening speed being too fast