The description says 'spring/summer', but these are great for the Autumn months too. They're water repellent up to a point, but no use in a downpour - use them in the same way as shoe covers.
The fit was perfect for me, I'm 6 foot nothing and a medium is just about right. If you're any taller then I'd get a large.
The material is lightweight, and they're easy to take off mid-ride and stuff in your jersey. The only downside is that they're a little tight around the elbow & forearm to start off with, but this improved after a bit of wear and a couple of washes.
Overall very impressed, likely to try some other Zennor products in the future.