Shive is the plug used to close the bunghole in a cask after filling. It resides on the top of the belly of traditional beer casks. Shives are made of wood (usually sycamore or oak) or plastic and driven into the bunghole by a mallet. Nylon is also used but is less flexible than wood as the latter can expand when in contact with the beer, ensuring a tight fit. Nylon shives, however, can be easier to remove for cask cleaning.

Size standardization has been slow and small diameter/thickness variations exist in the UK market. Example dimensions are 50–60 mm in diameter with a tapered thickness of 15–18 mm.

The shive has a thin central section which can be punched through to give a hole of 8 mm diameter for the addition of finings after filling. See finings. This is sealed with a tutmade from cork or nylon. The tut is removed and replaced with a spile for traditional cask beer venting. See spile. This hole is also the entry point for so-called blanket gas (carbon dioxide) that extends cask beer shelf life; it also provides the access point for a dipstick used to measure liquid/ullage content. Shives are used only once, then removed and discarded when the cask is emptied and washed.