This rubber turn-over closure with serrated stopper is 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.

• Store septa in a closed bag out of sunlight to retard blooming

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 suction sealing point.

For extra safety when using large bore transfer needles, fasten septum to bottle or flask opening with a wrap-it tie.