Strong and sturdy plate steel Shelf Dividers that hook on to the front of the shelf and can be moved along the shlef to the position you require> As soon as anything is leaned against the divider (files. binders or other items) the Shelf Divider locks in place. Two Shelf Dividers recommended to support files in 900mm wide cabinets and 3 Dividers recommended for 1200mm wide cabinets. Available in black or white to match your cabinet colour