The screw cap can be tightly closed as the 0.2 µm membrane permits an automatic sterile gas exchange, allowing safe pressure equalisation during the autoclave cycle, and at the same time ensuring the sterility of the bottle contents.
POA means "Price On Application". Items displaying POA instead of the sell price do so for a number of reasons, not least because we anticipate some additional information is required in order to supply the most suitable options/configuration to each individual customer.