The Rotring Rapidograph technical pens use Rotring"s unique capillary ink cartridges, invented to offer consistent ink flow. The way the Rapidograph is designed makes it virtually maintenance free. Each time a new ink cartridge is inserted, the pen gets a complete new pressure equalization system allowing for instant ink flow without leaks or blobs until the cartridge is empty.Each pen is fully equipped with one cartridge, a stainless steel drawing point, and a color-coded barrel and cap with double seal and clip. Refillable with Rotring Capillary ink cartridges only. Available in multiple line widths. Different ink color cartridges also available.Pen dimensions: Approximately 5.2 inches (13.3 cm) long and 0.4 inches (11 mm) in diameter.