Description General description Well-known as the best quality rubber turn-over closure with serrated stopper, Suba-Seal brand is available exclusively from Sigma-Aldrich. Ideal for air and moisture-sensitive chemistry procedures. After piercing with non-coring needle, rubber closes puncture, providing air and moisture tight seal to protect contents of vessel or container from atmosphere. This closure has turnover flange molded to grip outside of container neck promoting a double seal in conjunction with annular serrations on hollow plug. Annular serrations depress themselves against the inside wall of the bottle neck, making each serration a suctions sealing point. Storage Note for Natural Rubber Septa: Store septa in a closed bag out of sunlight to retard blooming, which is the formation of a whitish film on the surface of the rubber. Blooming is a natural process and does not affect performance. Remove visible bloom by washing or wiping off before use. Note: For extra security when using large bore transfer needles, fasten septum to bottle or flask opening with a wrap-it tie. See ties and accessory tool listings. Legal Information Suba-Seal is a registered trademark of Sigma-Aldrich Co. LLC