Just what I was looking for - I bought 2 and the build quality is the same between them, which looks pretty good, both work going up and down without issues.
They're also stable enough that my 5yr old can clamber up to sit on it by herself without it looking like toppling over.
Probably slightly wider at the top than expected, which means they don't sit under my table side by side exactly, but this isn't an issue (or an issue with the chairs!)