1/32 Thick X 6″ Long 20 Pair Ultra Thin Parallel Set ~ Parallelism is ±.0001″. ~ Paired ±.0001″ in height. ~ Hardness is RC 50~55. ~ Made from fine quality tool steel that has been stress relieved against distortion. ~ Parallels are also precision ground, hardened and blue finished. ~ Sizes included are one each of 1/2, 9/16, 5/8, 11/16, 3/4,13/16,7 /8, 15/16, 1, 1-1/16, 1-1/8, 1-3/16, 1-1/4, 1-5/16, 1-3/8, 1-7/16, 1-1/2, 1-9/16, 1-5/8, and 1-11/16″. Parallelism is ±.0001″. Paired ±.0001″ in height. Hardness is RC 50~55. Made from fine quality tool steel that has been stress relieved against distortion. Parallels are also precision ground, hardened and blue finished.