Sometimes reality is stranger than fiction.
Anyhow, Olympic Arms one-piece "ERing" gasrings. These are sorta like the MacFarland one-piece gasrings you see selling for more than they should. The rings are supposed to prevent gasring gap alignment and prolong replacement cycles. The story is that the standard M16's bolt uses three split gasrings, which means the rings are discontinuous and have a bit of a gap. Every time you clean your gun, you're supposed to stagger those gaps (120 degrees apart). Apparently, if the gasrings align just right, a terrible plague will befall the planet. Also, cycling problems. The funny thing is that I've pulled out bolts with lined-up gaps, and not noticed preceding cycling issues. The offensive condition looks like this:
Gap, not just bad for overpriced clothes
So, to "fix" the problem, what you do is pop out your old rings (all three), and worm the ERing on. It's a bit of a pain in the ass, and you'll probably want pliars for the task.
Grandpa's gasrings on the left (3), newfangled OlyArms ring on the right (1)
So when you get it on, you notice that because of its continuous nature, it's impossible to get a gapped condition:
No gap!
Hooray, we solved a non-problem. We've also introduced a new problem, though. Apparently the overall diameter on the ring is slightly larger, and the bolt is resistant to going into battery. The "solution", if you want to call it that, is to add lots of CLP, and shoot a bunch. You'll be good friends with your forward assist for the first couple magazines, I've found. Definitely don't rely on your rifle for duty until after the rings break in. As for ring life, I can't tell yet. I'll post more data, if you send me more ammo.
Conclusion: Once you get them broken in, they're good for peace-of-mind and maybe longer ring replacement schedules. If you can get them cheap, buy them, but don't pay more than $5. I got mine free from a friend. YMMV.
As usual, I don't work for Olympic Arms, and besides, they'd be nucking futs to pay me for this lukewarm review.