This Rotacator has a magnetic base and is used to adjust settings on any planer. Fine tuning your planer will eliminate nasty surprises such as non-parallel and chattered surfaces. Indicator rotates 360 degrees.
Woodstock Rotacator - used but works exactly as intended.
This is a very useful tool for setting up wood planers and jointers. New ones are very expensive, so I was glad I could find one that was used but in good shape still. This one fit that bill.