Vial Caps and Vial Seals are available with a wide variety of septa & liners. 11 mm diameter Aluminum Crimp Vial Seals have a larger opening to provide increased target area for needle penetration. Polypropylene Vial Caps are available in 8 and 9mm diameters and feature foam backed PTFE liners. 11 mm Poly Crimp™ Vial Caps permit an airtight