Staedtler Mars Micro Lead has a carbon fibre construction and is suitable for use in most mechanical pencils. The lead is flexible in design to be break-resistant and produces smooth, jet black lines. Plus, the unique packaging and neck of the tube enables you to pour all 12 leads into your mechanical pencil at once. It's suitable for use in most mechanical pencils. The lead is easy to erase for quickly removing markings. Each lead is size 0.5 mm with an HB gradation. The lead is break-resistant thanks to the flexible lead. There are 12 leads in this pack. It's suitable for use on paper and card.