Customer Rating: Summary: If you have Royobi AP10 you need this gauge. 2008-05-24 Comment: My surface planer needed new blades and I had no idea how to do replace and install new blades. I ordered new blades and this gauge. There were no directions. It took a long time to figure out how to use the gauge. A simple drawing or picture would have been a great help. The good news is that my old surface planer has a new lease on life.