It's a type of fastener consisting of a hexagon head and a screw (cylinder with half thread), which needs to be matched with a nut to fasten and connect two parts with through holes.
A4 Business Padfolio Portfolio with Letter Size Writing Notepads and document pocket and transparend card pocket. This simple design padfolio make it classic and popular. This make it fit for different market and usage. Such as school, office and organisa