Applicable to external horizontal opening window, with the width of the sash not larger than 650mm, and the weight of the sash not more than 30kg, window opening angle (⤠89 degrees). The support parts are made of high quality 304 stainless steel. The length (L) of the friction stay should be 1/3 to 2/3 of the width of the sash. Please consult the manufacturer about special specifications of the external open window friction stay.