Sizes: 17,7 mm. x 7 mm.
The standard pen for writing is the HB, a hard line and dark pigment balanced. This system was developed in the early twentieth century and indicates the hardness of the pencil with a scale from BBB, the softer, until HHH, the hardest. The more letters you have, most are hard or soft. BBB is less soft mark with BB, then B will follow, and then it would come the hard starting and an H increased up to three.