It’s essentially a kind of non-zipped turtleneck / cycling top type number, with a high collar, but short sleeved and otherwise quite light to wear.
I have one already in the old red style - they used to have two distinct types, one version with stripes around the collar and one version with stripes up on the front.
In this new design, they have combined both, which works really well. The colours (a slightly shifted palette compared with the summer set) and the positioning of the stripes also give it an intrinsically sixties vibe - it’s a well-designed warm weather top. My girlfriend described the overall colour as "rust".
Ok slight problem in that the warm weather is sort of nearly over, but I couldn’t resist the strong autumn shade.
Tbh I’m glad I’ve now got a variation to wear because I’ve definitely over-used my first one!