A "slotted flat blade screwdriver" is a hand tool that dates back to the 1500s. It features a flat bladed tip for turning, fastening, or loosening screws and bolts. The flat-blade screwdriver is a very versatile tool that can be used on fasteners of various sizes while offering great leverage. It is recommended to use slotted flat-bladed screwdrivers with stainless steel shafts and handles to prevent corrosion. The image below shows how a slot can be created in a flat blade screwdriver by placing it inside a drill bit hole of the correct diameter. By extending the handle beyond the end of the slot, you can twist the blade to either sharpen it or change its angle of attack. This tool can be used to remove small screws and nuts, but it will not work on screws with washers because there is no way to get past the washer thickness. A phillips head screwdriver is needed for those situations. Also useful for opening containers. Some plastic bottles are made from polycarbonate material which is almost impossible to cut with standard scissors. However, they are easy to open using a slotted flat-blade screwdriver. Finally, this tool can also be used as a pry bar. It's helpful to have one around when working with hard-to-get-at screws or bolts.