Saw Log Marking GaugeQuick Description. Saw log marking gauge to easily mark out lines on the log. Why it is cool. Gauges don't get much easier to use than this cracker. It can easily and quickly mark out lines on your sawing log with clean accurate lines with the provided crayon. Simply insert the crayon into the hole at the required distance and roll the gauge around the log for a perfectly straight line that is consistent and easy to see. When the crayon gets blunt,