For use in wood barrels. Pre-drill a hole with the included 7/64 bit before installation. The smaller 4d nail is then pounded two-thirds way into the hole, plugging it. Leave enough shank exposed so the nail can be later removed. The 6d nail should be kept in reserve, in case the hole in the barrel becomes too large for the smaller nail to plug it (a rare occurrence). This is the best way to pull a sample and test wild beers without breaking the pellicle, the way typical siphon methods would.