Overall lengthThread lengthThread + Neck lengthShank lengthShank dia.Size of squareLength of square
LℓnℓsDsKℓk
SizeClassCodeChamferL (mm)ℓ (mm)ℓn (mm)ℓs (mm)Ds (mm)K (mm)ℓk (mm)LobeTYPE
M16 × 1.5ISO2XRM016OBOCTB2P10018-511291283
M18 × 1.5ISO2XRM018OBOCTP4P11020-5614111483
M18 × 1.5ISO2XRM018OBOCTB2P11020-5614111483
M20 × 1.5ISO2XRM020OBOCTP4P12520-6416121583
M20 × 1.5ISO2XRM020OBOCTB2P12520-6416121583

Number of oil grooves: M6 = 5, M8 = 6, M10 and larger = 8 For M6 and smaller, external centers of 2 thread chamfer taps are removed.