• Brand = Staedtler
• Model Number = 250 03 HB
• Colour = Black
• Pack of 12
• Manufacturer = Staedtler Mars GmBh & Co.
• Easy Erase, Break Resistant Leads
• Smooth Gliding Leads - Jet Black Lines
• Suitable for use with All Mechanical Pencils

0.3 mm is mostly used for drafting purposes, but it's also used for writing where the user prefers a very fine line.

However, the very fine width makes it inherently more prone to breaking than the larger diameters. The widest range of lead grades available in 0.3mm is currently Uni's Nano Dia lead.

0.3 is also more Fragile than 0.5, so there's more breakage during manufacture, which raises the overall cost.