Self-sealing stem bolts are mysterious components. In 2369 Jake Sisko and Nog trade 500 wrappages of Cardassian yamok sauce for 100 self-sealing stem bolts from a Lissepian freighter captain. The field of application of the self-sealing stem bolts is never revealed; not even Miles O'Brien, who otherwise can fix anything, knows what they are for. (DS9: "Progress").
In 2371 an opportunity presents itself to Quark to get rid of a stash of self-sealing stem bolts he has had lying around. The prospective buyer claims that with the stem bolts, they will be able to triple their production of their "reverse-ratcheting routing planers". (DS9: "Prophet Motive").
Whenever something is (seemingly) useless, a metaphor or simile that includes self-sealing stem bolts might be in place.