This 80 grit fine grit abrader will likely become the standard and the next BIG advancement in modern knapping. The “Ultra 80” and the “Super150″ are for finish work. They are specially formulated for working hard stones like flints/cherts. The bond in these abraders is softer than traditional grinders so that they replenish grit faster, leaving you with a sharper abrading edge for faster and more consistent platform preparations. These have become my personal favorite! I highly recommended these for knappers ready to go to the next level of thinning and control. The dimensions are 4 x 2 x 1/2”.