An industrial component whose purpose nobody on Deep Space 9 can explain, acquired by the hundred gross by Jake Sisko and Nog in the episode Progress.
Self-sealing stem bolts are a piece of engineering hardware that became one of Deep Space Nine's running jokes, because no character who handles them, Chief O'Brien included, has any idea what they are for.
They are introduced in the first-season episode Progress. Nog and Jake set up their first business venture by trading Quark's unwanted yamok sauce to a Lissepian freighter captain for one hundred gross of the bolts, originally ordered by a Bajoran who could not pay. The boys then exchange the bolts for a parcel of land on Bajor, which Quark turns out to need, giving them a profit in latinum.
The bolts are mentioned again in later episodes, and other Star Trek series have dropped the name in as a knowing reference.