The First thing I noticed when I touched them is that the plastic is a bit soft in comparison to every cymbal sleeve I use f.e. Yamaha, Dixon, Gibraltar. It doesn't feel cheap, but only time will tell how long will they last.
The second thing I noticed is that they will not screw all the way on my Yamaha cymbal stand (8 mm thread), although it does say that it fits 6 mm and 8 mm cymbal stands.
So based on that, they fit the 6 mm cymbal stands, but they will just screw halfway through on an 8 mm thread, which is not a stability problem but my OCD kinda reacts to it.
Now after long hours of practicing, jamming etc. They seem to be perfect for what they are supposed to do... My cymbal will not fly away during hard playing and even my sizzle chain will not fly out.
The negative thing I have to say though and probably a really important one, is that I think that the vibrations from the cymbals travel easily to the cymbal stands with these sleeves, and I noticed it because I can hear a different humming sound during the cymbal sustain which is really annoying...