Published in the Journal of Infusion Nursing, 2021, 13 needleless connector (NC) brands were tested for bi-directional flow and reflux. Out of all the categories of NCs (positive displacement, negative displacement, neutral displacement, and anti-reflux), the anti-reflux category had the least amount of reflux and the only devices capable of controlling mechanical and physiological pressure changes. This confirmed only ani-reflux NCs were functioning as neutral, which suggested the neutral NC-market category may be misleading.