Review on HFS Steel Parallel Parallels Hardened: Ultimate Precision and Durability for Industrial Applications by Lamont Manjrekar

These parallels are ok for the money. The swallowtail is rough and hard. I've measured with a micrometer at various settings and got slightly different results from 0.0001 to 0.0004 along the length of the parallel. They appear to be capped and then sanded on all 6 sides and the finish quality is 6/10. They appear to be the same ones pictured by Accusize which are about twice the price. Not very good but if I wanted something more I would buy Starrett, Brown & Sharp or Mitutoyo. They're good for a quick setup in the store, but far from being a test/verification set.