Closures with pre-cut septa, pk of 100 size 11 mm, Snap cap, blue polyethylene, red PTFE/silicone, thickness 1.0 mm: 29497-U: Closures with pre-cut septa, pk of 100 size 18 mm, Magnetic screw thread cap, UltraClean, red PTFE/silicone, thickness 1.5 mm