It appears that at the slightest application of pressure, this stitch holders snap like twigs. Save yourself the trouble and just buy the one's from Knitter's Pride or Clover both of which are really great!.
I decided to finally purchase an interchangeable set after getting tired of moving around my collection of fixed circulars. These are all around great needles. Sharp but not too pointy that you're splitting your yarn. The joins with the cables are sturdy and smooth. I have not had issues with the yarn catching onto them. The tips attach securely to their cables and the cord stoppers work as described. They included a cord key with each of the cables but I have not had to use them. Simply twisting the tips onto the cords themselves works to secure them.
The joint ends do not spin however. I know this can be an issue for people who often get kinks in their circulars but this has not been an issue for me. If you want interchangeables that spin on their cables I would suggest the Addi set or the HiyaHiya sets.
Overall, this needle set has performed very well for me. If you're looking into purchasing your first interchangeable set, I would highly recommend these as an economical and effective needle set!