A 23–25-gauge scalp vein (butterfly) needle or a 23–25-gauge venipuncture needle (safety-engineered self-shielding), 1- or 3-mL syringe, povidone-iodine and alcohol swabs, 4 × 4 gauze pad, gloves, 1:1000 heparin or self-contained blood gas kit, high-intensity fiber optic light for transillumination, or a Doppler ultrasound (optional, can be useful to locate the artery). Smaller needles preferred (25 gauge for preterm infants, 23 gauge for term infants).