Portable Pencil Hardness Tester Coating Hardness Testing Device Scratch Tester
Grip the center of both wheels with your thumb and middle finger. Hardness grades, standard pencil set from softest to hardest: 6B, 5B, 4B, 3B, 2B, B, HB, H2, H3, H4, H5, H6, H (13 pencils total). After testing, rotate two sides, secure, and test again.