Fine for warm days, but it's cold days when you need armwarmers most...
This is a thin armwarmer that's better employed as an extra layer at the start of a warmer ride than any kind of winter protection.
They're nicely made from a tightly woven Lycra, the seams are flatlocked and there's a minimal reflective logo at the wrist. The top gripper is snug without being restrictive.
When you first put they actually make your arms feel colder, which is weird - maybe it's because they don't have a roubaix inner layer. Once you're riding and warmed up they do improve, but they're thin and not windproof so the benefit isn't as pronounced as you'll get with some armwarmers. They're light though, so easy to stash in a jersey pocket.
All in all, there's better options out there and the Ozons don't really stand out. They're fine for Summer or as an extra layer of protection down the track, but they're not thick enough to cope with year-round use.