Abstract: A cell-culture flask which may be readily charged under sterile conditions, having a cap capable of covering its neck opening and an orientation strip attached to the flask at one end and to the cap at the opposite end; the orientation strip supports the cap in a first position in which the cap overlaps and covers the neck opening without sealing it; the strip is flexible to allow manual displacement of the cap away from that first position to a position in which the cap does not obstruct the introduction of a pipette into the opening; in the absence of displacing forces, the strip has a memory which returns the cap to the first position.