concealed door closer 1,material: aluminium 2,color: aluminium color 3,door width: 500mm-2300mm 4,door weight: 20-90 1, Item name: Concealed Door closer2, ... safety. After special design, used imported spring, imported high temperature and resist freeze and wearable oil, lighten the ... strength when open and close the door. Make it more easy and smooth.. High the strength and leak prevent configuration ...