In reply to Blue Straggler:
They can work well if they can be fitted properly i.e designed for the type of chair, tight fit. I have had one for a folding chair for more than 20 years now and it’s still fine. Last year I bought two for newer folding chairs and they are fine.
Common aspect - they were designed for the type of chair (same manufacturer and of a profile and size of frame etc. to fit and grip will). Never had any break, or come off accidentally. Maybe I’ve just been lucky of course .
The type in the photo may just slide and cause a rotation of the holder which may or may not cause it to fall off in use. My 20 year old one is of that type but stays put as it “grips” the chair frame.
Edit: Forgot to add it does also depend on the ground the chair is on. The softer more uneven, the more that type of chair will flex and this will cause movement in the holder and this may cause it to loosen. Firm/solid ground mine never move, but if on softer, once seated re adjust the holder helps.
Post edited at 11:31