The hardness of Grade F is between HB and H (…. B, HB, F, H, 2H …..).
* F stand for the word “Firm”.
What is special about Nano Dia?
In order to achieve required strength, pencil leads are normally made with aligned graphite in high density. However, these graphite particles are subject to friction with each other, which results in loss of smoothness when drawing.
With Nano Dia leads, however, the graphite is evenly mixed at a molecular level with over 400 million nano diamond particles in each 60 mm graphite lead, giving it high strength and durability, and, by reducing friction, endowing each lead with smooth flow performance and a strong dark line.
Lid has a two-stage, sliding action to allow you to adjust the number of leads dispensed each time.