Concealed window hinges are made of stainless-steel mounting plates and steel link arms.,Link arms are finished in a corrosive resistant e-gard coating which comes in a light gray color.,Widely used with crank-out & push-out casement windows, crank-out & push-out awning windows, tilt-in hopper windows & transom windows.,Freely adjustable,smooth and easy to operate when open and close.,The package includes fasteners (Fit for M4*16/M4*18/M4*20 screw), please pay attention to the size before purchasing.