Overall lengthThread lengthThread + Neck lengthShank lengthShank dia.Size of squareLength of square
LℓnℓsDsKℓk
SizeClassCodeChamferL (inch)ℓ (inch)ℓn (inch)ℓs (inch)Ds (inch)K (inch)ℓk (inch)LobeTYPE
7/16-14UNCH951111030982P3.9370.512-2.0080.3230.2420.40683
7/16-20UNFH851101031014P3.9370.512-2.0080.3230.2420.40683
7/16-20UNFH851111031012P3.9370.512-2.0080.3230.2420.40683
1/2-13UNCH951101031114P4.3310.591-2.2050.3670.2750.43783
1/2-13UNCH951111031112P4.3310.591-2.2050.3670.2750.43783
1/2-20UNFH851101031154P4.3310.591-2.2050.3670.2750.43783
1/2-20UNFH851111031152P4.3310.591-2.2050.3670.2750.43783
9/16-12UNCH1051101031264P4.3310.709-2.2050.4290.3220.583
9/16-12UNCH1051111031262P4.3310.709-2.2050.4290.3220.583
9/16-18UNFH951101031294P4.3310.709-2.2050.4290.3220.583
9/16-18UNFH951111031292P4.3310.709-2.2050.4290.3220.583

Number of oil grooves : 1/4 and smaller = 5, 5/16 = 6, 3/8 and larger = 8 For 1/4 and smaller, external centers of 2P chamfer taps are removed.