Correct me if I'm wrong, knowledgeable artist peoples, but I believe #2 pencils are HB, right in the middle.
My pencil set goes from 6B (very soft) to 6H (very hard). The gradient from softer to harder would look something like [...3B, 2B, B, F, HB, H, 2H, 3H...], F and HB being right in the...