If I'm reading this right the Sigma II would be excellent for all steels although they might be overkill for 01 and A2 with only a marginal improvement over Bester/Imanishi etc. Lee Valley suggests soaking the Sigma IIs for a few minutes but doesn't say whether they can be left in water all the time. They suggest spritzing the Imanishi 8000 (like the Shaptons) As I'm in Southern California leaving stones in water is fine -- no real frost! I'm more confused than ever with the choices out there. What to do.....????