(bySteve Smith, Castelli Brand Manager)
We can officially only rate these warmers at UPF 50+, but in our laboratory tests they actually blocked 99.8 percent of damaging UV rays. We used a polyester base that is not only more effective than nylon at blocking UV rays but is also much better at keeping you dry, which means these Sleeves are better in both cooler and warmer conditions. We’ve kept the construction very clean to eliminate seams that can rub, and we used our double-sided silicone elastic to make sure they stay in place. They fold up extremely small, so they’re great to stick in your pockets for your next big mountain day.
Features of the Castelli UPF 50+ Light Arm Sleeves:
Solare fabric keeps the chill off without causing overheating
UPF 50+ protection
Polyester based for excellent moisture management
Double-side silicone elastic at top for excellent grip