Overview The Combi-Stopper® is a sterile, polyethylene closing cone with both male and female Luer-lock fittings. It offers contact-free closure of open male or female Luer lock and Luer slip connections — making it ideal for safely sealing infusion systems, syringes and IV catheters. This solution is universally suited for adults, paediatric and neonatal patients with no age- or gender-related limitations.