Fits 8L and 15L Vertical Sidearm Spinner Flasks. Sidearm fittings for media handling can be used to introduce medium aseptically into larger Spinner Flasks with vertical sidearms during cell culture to enhance the productivity of the cell culture. Together with sensor probe fittings and gas handling fittings, they allow Spinner Flasks to operate as bioreactors when they are attached to appropriate cell culture controllers at costs considerably below those of traditional bioreactor vessels with expensive stainless steel headplates. The fittings are comprised of a PET insert with a higher temperature resistant o-ring of EPDM and a polypropylene sealing cap. Stainless steel tubes (1/4” OD) are held in place by modified polyphenylene oxide thermoplastic nuts with integrated ferrules. The fittings are completely autoclavable.