Self-sealing stem bolts as suggested by their name were stem bolts that sealed themselves. The field of application of the self-sealing stem bolts is unclear; even Miles O'Brien, the Chief of Operations of Deep Space 9 was unaware of their exact use. (DS9: "Progress")
In 2371, an opportunity presented itself to Quark to get rid of the stash of self-sealing stem bolts sitting in Cargo Bay 11. He offered them to a wealthy prospective buyer named Emi for ten bars of gold-pressed latinum. Emi claimed that with the stem bolts, her family would be able to triple production of reverse-ratcheting routing planers. Emi, however, was told by Grand Nagus Zek where she could get the bolts at wholesale, for a much reduced price. (DS9: "Prophet Motive")
In late 2375, O'Brien explained his reasons to Dr. Bashir for taking a teaching post at Starfleet Academy, he quipped "somebody has to teach you officers the difference between a warp matrix flux capacitor and a self-sealing stem bolt" (DS9: "What You Leave Behind").