This 2 leg lyophilization stopper is manufactured from the highest quality raw materials and tolerances for flange heights on stock stoppers are held to ±0.010in. Components manufactured to yield exceptional dimensional stability. This reduces the possibility of legs sticking to each other. Stoppers are designed for use in freeze-drying applications. Durometer is a measure of the resistance of a material to indentation. The higher the number, the greater the resistance. The term durometer is often used to refer to the measurement, as well as the instrument itself. Slotted plug. Autoclavable. Black. Halobutyl/60. 60 Durometer. For 31 I.D. x 43mm O.D. Vials. Wheaton #: 224100-503.