Silent buffer hydraulic door closer, silent buffer smooth and unobstructed, waterproof aluminum alloy shell, wear-resistant and durable.Positioning model, the door will stop at 90 when the door is opened to 90, and the door will automatically close when it is less than 90.Ultra-quiet operation, bid farewell to closed door bombing, multiple noise reduction, using high-toughness 60SI2Mn spring 2 million times without deformation, rejecting abnormal noise caused by dislocation.S: Door width is less than 0.9M, door weight is 25-45kg, choose small size. It is suitable for installation in lighter household door, kitchen door, bathroom door, wooden door, hollow door, framed glass door, etc.M: Door width is less than 1.1M, door weight is 40-65kg, choose medium size. Suitable for household conventional doors, security doors, fire doors, fire doors, stainless steel doors, framed glass doors, etc.L: Door width is less than 1.2M, door weight is 60-85kg, choose large size. Suitable for heavier security doors, fire doors, warehouse doors, fire doors, etc.The door closer is installed without separation, regardless of left and right, and the standard installation of the speed control valve faces the hinge side.When installing the door closer, the body can be installed on the door or on the door frame.One-piece high-gloss oil layer, one-piece sealing glaze treatment, wear-resistant and scratch-resistant.The shell is processed by one-time clamping, and the processing is completed in multiple processes in sequence.The operating temperature range is -30-40, which is suitable for the cold winter in the northern region. The temperature drops to dozens of degrees below zero, and the door closer still operates freely.The rotating shaft of the connecting rod rotates softly and smoothly, ensuring the normal opening and closing of the door.Adjustable telescopic arm, the telescopic arm can be adjusted and retracted freely, even if the door sill door leaf is not on the same plane, it can still be installed smoothly.The square mouth anti-slip twist, the connecting rod and the main body are connected by a square mouth anti-slip twist, which is more firm and not easy to fall, and has a high safety factor.[Note] Before the door closer is installed, the gear shaft of the door closer cannot be rotated 180 degrees, otherwise the door closer will be damaged and cannot be used. Note 1: The door closing speed is slightly faster at 180 to 15, but at 15 to 15. When the temperature is 0, try to slow down, and the door can be fully sealed to prevent the door speed from being too fast, resulting in noise caused by the collision between the door and the door frame and damage to the door lock.[Speed control]: The speed of opening and closing the door can be adjusted in two stages.