This essential child safety device is designed to limit opening of a window to 100mm. It can be released to facilitate full opening of the window, it automatically re-engages restricted position on closing of the window. Easy fit onto window (screws provided) Fits inside 'euro groove' opening channel on a upvc window Designed to restrict outwards opening to 100mm Manufactured from Steel C1008, Silver Trivalent finish to meet BS 1670:1998 Grade Available in left and right hand variants to suit requirements (see image for positioning) .