... about 58HRCApplicable to families, and industrial applications.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Existing specifications:BK 638-7A: Cross +PH1 +PH2, Slotted -5 -6, Six edge-type ... 4 5 6.BK 638-7B: Cross +PH0 +PH1 +PH2 +PH3, Slotted -5 -6 -7 ... .BK 638-7C: Hexagonal T10 T15 T20 T25 T30, Y-type Y2 ...