These are really good for the price. Good range of sizing, although small is small!
The smaller sizes are really very tight! Otherwise for the price they're good and do the job.
Exactly what is advertised
No need to worry about it getting trapped and having an awkward visit to the ER. Much safer than metal ones. I wouldn't want an angle grinder anywhere near my bits if the ring wasn't sized right. The extra rings not in use are great for holding vibes in place when you're getting creative.