Fit and function is just right. I wear this under my cycling jersey most morning rides. It doesn't add a lot of warmth, you can really feel the wind coming into the sleeves. Just enough to take the edge off on the warm up and not too hot for the interval rides. I wear it in the mid 50's with jersey and vest or no vest depending on high or low 50's. The build quality and stitching looks to me like it'll hold up well. I've worn/washed maybe 30 times and it's still as good as new.
I use these arm warmers between spring and fall, including cooler summer mornings or in the mountains. They are comfortable and even keep your arms warm in light rain, though they aren't waterproof. I like the left-right specific fit. I like to order a size smaller than what the charts might suggest, because I like a snug fit that will stay up after many uses. Even the size small has good length, which is not the case with some other brands. They may be a bit pricey, but I think they're worth it.
I've been using these Castelli arm sleeves for years. I am happy to minimize the amount of sunscreen I use on my body while maintaining good UVA protection. In addition, I am able to use these even in the hottest weather as the sweat on them wicks off at speed and has a decent cooling effect. The only think about them is the price and the fit - it's tough getting the upper arm attachment flat and comfortable at tiimes and the wrist area can sometimes be loose.
This has become my go to skullcap for several reasons. First the fit on my head is great as it sits right above my ears when fully stretched out without feeling too tight. I actually don't feel it once I start my rides. It stays cool during hot days and protects my baldish head from sun burn. The combination of a sweat band and mesh keep my face dry from sweat. At first before you break it in its a bit uncooperative when trying to put on. After a few washes it stretches just a bit and becomes easier to put on. I have purchased generic less than equivalents for cheap from Amz but they typically are poor fitting either too big/long and a waste of money. I own both the black and white equivalents to match either my white or black helmets. I am a daily rider and have multiple Castelli Summer Skullcaps so I can ensure I have a clean one available at all times.
