2.0 mL, 11 mm Poly Crimp-Top/Snap-Top Caps and PTFE/Butyl Rubber Septa, Clear, 1000-pk. 2.0 mL, 11 mm Aluminum Crimp-Top Seals with PTFE/Silicone Septa, Silver, 1000-pk. 2.0 mL, 11 mm Aluminum Crimp-Top Seals with PTFE/Natural Rubber Septa, Silver, 1000-pk.