As far as diameter tolerance, ovality, straightness and surface quality are concerned, centreless ground bars are far superior to all other executions of round bars. In most instances, the product can be used directly, as axles for example, with little or no need for further processing. The diameter tolerance of stainless-steel ground bars is usually h8 as stipulated in ISO 286 - 2 and which is a zero-minus tolerance. In other words, the actual diameter is marginally less than the nominal one.