Very useful for template and pattern routing where the template is on top of the workpiece. Ball bearing guide rides against the template for an exact duplication. If used on a router table, the pattern will be on the bottom, below the workpiece.
WARNING: Drilling, sawing, sanding or machining wood products can expose you to wood dust, a substance known to the State of California to cause cancer. Avoid inhaling wood dust or use a dust mask or other safeguards for personal protection. For more information go to www.P65Warnings.ca.gov/wood.