One black reusable V1 60 unit injector pen. This pen uses standardized 3 ml cartridge. The V2 model refers to a specific version of a standard design. Some of the Key features are Reusable design: The device itself is reusable, unlike disposable pens that are discarded after a single use. Wide compatibility: The pens are designed to be compatible with a variety of 3 mL cartridges that conform to ISO standards (specifically ISO 11608-3 cartridges) Color: The "black" designation refers to the color of the pen's exterior. NOTE: It is important to note that this is NOT A MEDICAL DEVICE. It is for use only with established research protocols.