Used on standard GL 45 bottles*. The gas absorption attachment (GAA) is filled with an asborbant, for example sodium hydroxyde liquid, in order to capture one or several components from the gas. It is usually used in aerobic respiration where produced carbon dioxide is removed directly from the headspace which creates an underpressure that drives oxygen from an oxygen source to the reactor.
Also, please see Gas Absorption Attachment, Package 3 (ART NO 12-0201-02)
* Fits most standard GL 45 bottles but variations in manufacturers implementations can occur.