I can vouch for this, they’re called circlips. In the factory I worked in they had a polished concrete floor, fuck me you would not believe how far small items would go on that sucker when dropped.
In a moment of what now seems like madness, I dismantled my Snap-on screwdriver, the circlip came of ok using the pliers I ground down especially to remove it, but then my confidence took a hit when I removed the cover and a small (I’m talking 3mm long, and 2mm dia at it’s widest) nipple was propelled skyward by the spring that the cover was holding in place. I ran round like a twat sweeping every bit of crap up in a 10 metre circumference, then sifted through it, found the sucker as well. You live and learn…Still got the screwdriver, bought it in 1989 so everyone who laughed at the £24 price tag then can fuck right off as well.