When it comes to the sizing of woodscrews it is still very common to find measurements in both metric and imperial. The diameter of a wood screw is either given in a gauge (imperial), or in millimeters (metric). With the imperial gauge, a number is used, i.e. 8 gauge. A larger gauge number means a larger diameter. Screw gauge numbers actually correspond to a particular fraction of an inch in imperial measurements.
Woodscrew lengths are also often shown in either metric or imperial, or sometimes both.