This popular pen set is standard of the industry.

Koh-I-Noor 7 Pen Set This technical pen set includes line widths of 3x0, 00, 0, 1, 2, 3, & 4. Packaged in a convenient flat shaped, hinged-lid plastic case with a push button release. Each set includes a 3/4-ounce bottle of Universal drawing ink and nib keys for changing tips.