This tool places a capsule - i.e. a metal cap with pegs at the bottom (1) - over the spigot of a wine barrel, so that it is sealed and ready for transport. The tool is knocked with a hammer and the capsule is driven into the wine barrel.
(1) The capsule can be marked with the mark (number) of the seller or with motifs related to wine growing such as a bunch of grapes. Yellow capsules are used for white wine, while red capsules are used for red wine (BRUNET 1925: 262).