Advancing pen having individually capped cartridges

A cartridge for use with an advancing pen, comprising:

• a cartridge body, the cartridge body containing contents;
• a seal, the seal retaining the contents within the cartridge body;
• a cartridge tip, the cartridge tip located substantially within the cartridge body and in contact with the contents and penetrating the seal, the cartridge tip withdrawing the contents to apply the contents to a desired surface;
• a retaining cap, the retaining cap sealing the cartridge tip and the seal, such that the retaining cap must be removed before the cartridge tip can deliver the contents to the desired surface;
• and
• an alignment tab, the alignment tab protruding radially from the cartridge body, and extending along the length of the cartridge body, said alignment tab serving to prevent rotation of said cartridge body within a dispensing pen by fitting into a longitudinal slot located on an interior surface of the dispensing pen.