PIERCEABLE CAP

A pierceable cap (211) maybe used for containing sample specimens during storage and transport. The pierceable cap may prevent unwanted escape of sample specimen before transfer with a transfer device (25). The pierceable cap may fit over a vessel. An access port (223) in the pierceable cap may allow passage of a tip (41) of a transfer device through the pierceable cap. Multiple frangible layers maybe disposed across the access port. One or more extensions (227) proximate to a lower frangible layer (215) may rotate around one or more coupling regions (247) during insertion of the transfer device. The movement of the one or more extensions may pierce the lower frangible layer to create airways and allow air to escape from a vessel at a reduced velocity. Upper frangible layers (216) may prevent escape of materials from spaces intermediate between the lower frangible layer and the upper frangible layers.