This Vertical Step base is perfect for creating chatter free cuts in solid surface and wood using router bits with bearings. One half of the base has been milled 20 thousands deeper than the other. Set your router bit for depth using the milled side of the base. Make your first pass using the thicker, non-milled side of the base. Rotate the base to the milled side and the bit is lowered slightly creating a second "chatter free" cut. This base is great for use with our LubriCool Syytem when routing solid surface materials.This base is currently drilled for a Porter Cable 4 Hole Router and the Festool 2200 Router. This base come in either blue or red.