This solid leakproof Top Works? Silicone Top combines a flexible platinum-cured silicone insert with a polysulfone screw closure. High-purity platinum-cured silicone insert is fused to the stopper to form a one-piece closure system ensuring fluid contact areas are crevice-free to eliminate cross-contamination This unit has no ports. The autoclavable leakproof system permits easy aseptic media transfer from common bottles. It has been designed with food-grade and noncytotoxic materials to meet USP VI requirements. Note: Not for use when creating pressure or vacuum conditions with containers that are not rated for pressure or vacuum applications. Not intended for invasive use. Autoclavable. Leakproof. Material: PP with platinum-cured silicone insert. Closure size: 83B. Number of ports: none (solid insert). Sold individually. Nalgene #: 2135-8300.