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 seal by hand or use a standard crimping tool. Snap Seal ™ Vial Caps may be snapped on and off by hand which eliminates the need for metal crimping and decapping tools, thus reducing potential hazards due to sharp aluminum metal edges.