CNC Spoil Board Cutter Inserts 14 x 14 x 2.0 C-4 Grade.  Use these for use on the spoil board as well as solid surface when planing down.  The C-4 grade is a higher, harder grade than the standard carbide.  Only a few dollars more will save you more money.  C-4 will last longer and work better with solid surface materials.  Comes in a pack of 10

SI-141420-SP