About self-sealing stem bolts
What are self-sealing stem bolts? They are incredibly advanced, and useful, pieces of equipment, used in the production of reverse-ratcheting routing planers, among other obvious applications.
Self-sealing stem bolts are usually used in large quantities, such as a hundred gross. They're used in heavy industry - the average person will probably have never seen a stem bolt in his or her life. But no real industrialist would be caught without tens of thousands.
A prospective buyer should beware, as not all stem bolts are of the same quality. Indeed, some of the more shoddy ones do not perform their main function adequately.
Most importantly, self-sealing stem bolts are a relatively recent invention, one which suddenly made entire warehouses of stem bolts - of the non-self-sealing kind - obsolete. Naturally, many less scrupulous businessmen have been trying to get rid of those, for decades. That is why you must never buy stem bolts with first taking a random sample and checking whether it is able to automatically seal itself, when activated.