You might consider a surface plate a basic precision instrument. It is the solid, flat plate or base upon which a lot of precise work is done. Because it serves as a gauge in determining the accuracy of a plane, it is the flattest of flat. But this versatile precision instrument (usually a granite surface plate) can also be used as a surface tool on which to perform precision assembly or machining, as well as to inspect small items, components and parts to be repaired. Speaking of true surfaces, be sure to check out our surface tester offerings. Products vary by weight, thickness, flatness unilateral tolerance, dimensions and other considerations.