The GL45-thread screw caps are supplied with 2, 3 or 4 outlets or ports as they are known. By applying positive or negative pressure, liquids and suspensions can be pumped out of or into the bottle via the screw cap. Different hose diameters can be fitted by using a universal GL14 hose adapter with various inserts. A supplementary 0.2 µm membrane filter can be used to provide a sterile pressure equalization on one of the outlets.

The system is modular in design. Users select the components needed in accordance with their requirements and the application in question. All the individual parts are mutually compatible and fit original DURAN® laboratory glass bottles with GL45-threads.