A Butterfly or scalp vein set, also known as a winged infusion set, is a specialized device used for drawing blood from a vein and giving medication or intravenous (I.V.) therapy into a vein. It consists of a very fine hypodermic needle, two flexible “wings” – resembling the wings of a butterfly – flexible transparent tubing, and a connector. The connector is attached to another device i.e. to a vacuum tube or collection bag to draw blood, or to extension tubing from an infusion pump or IV bag to deliver medication and fluids. While all scalp vein sets carry a similar design, there are variations. Newer models include a slide and lock safety device to prevent accidental needle-stick injuries and reuse of used needles, which transmit infectious disease such as HIV and Hepatitis B and C. Though properly secured butterfly needles can be left in a vein for up to seven days, they are more frequently used for short-term infusions.