A winged infusion set—also known as "butterfly" or "scalp vein" set—is a device specialized for venipuncture: i.e. for accessing a superficial vein or artery for either intravenous injection or phlebotomy. It consists, from front to rear, of a hypodermic needle, two bilateral flexible "wings", flexible small-bore transparent tubing (often 20–35 cm long), and lastly a connector (often female Luer). This connector attaches to another device: e.g. syringe, vacuum tube holder/hub, or extension tubing from an infusion pump or gravity-fed infusion/transfusion bag/bottle.
Newer models include a slide and lock safety device slid over the needle after use, which helps prevent accidental needlestick injury and reuse of used needles, which can transmit infectious disease such as HIV and viral hepatitis.