Half Thread Hex Bolt is an engineering class mechanical tool which is widely used to join to half of the cylinder blocks of the car engine. It can also be used to connect the cope and drag used for the casting production. The head is machined in the form of a flat hexagon for better gripping with the tools like spanner and pliers during the tightening and loosening application. Its long cylindrical shank is provided with mechanical threads on half of its length from the free end.