A wrench or spanner is a tool in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning.
There are many different size head of bolt,we need right size spnners to successfully tightening or loosening nuts and bolts ，how to choose？To answer that, Fistly we need to consider both the type of thread on your nut or bolt ， Whether you are dealing with metric or imperial ro UNC measurements, selecting the correct size is important to avoid damaging the fastener or the tool.
Save a spanner size chart,This chart helps you quickly identify the right spanner for the bolt
For example of DIN933,931hex bolt ,the following is the contact with bolt size and spnner size.
We are the professnion factory (ZJB Fastener )of bolt and nut ，share the useful information for your works.
