Tested it on one of my hardest Harts and a 2.5 day beard. Nice finisher. Very little feedback unless you apply a little torque. I would equate this stone to a well-burnished surgical black arkie. Scratch pattern does look like a 10K +/- . Very keen edge. I like it and would recommend it. As with the PHIG (and any natural) there will typically be variances from stone to stone.