90/1.03 carbon range (Also known as clock spring steel.) This product, while similar to general description under heading of Tempered Spring Steel Strip, is manufactured and processed with great and extreme care exercised in each step of its production. Manufactured from carbon range of .90/1.03 with Rockwell range C 48/51. Clock spring quality has been ground and polished with edges dressed. It is usually supplied hard blue in color and has a wide range of uses, such as coiled and flat mechanical springs, ignition vibrator springs, springs for timing devices, springs for the electric and electronic fields, steel tapes, rules, etc.