What is the correct name for this?

I'm trying to find the proper name for what we called a "double ender" (which can't be the proper name (??). It is a metal "bolt", with wood screw threads on one end , and "regular" threading on the other end to put hex nuts, washers, etc. I may need them to attach a a cover to framing members ( using the wood screw threads), but have the cover be removable -thus the "regular" threading. (the wood screw threadings holds the "bolt" in place, and the regular threads with hex nuts/washers etc. holds the cover.) Thanks in advance.