Lightweight and breathable arm coverage has been all the rage for riding under the power of the sun, whether when cooler temperatures belie the impact of UV rays or the sun is high and the temperature is accordingly hot. With a rating of UPF 50+, Castelli's Light Arm Skins keep the chill or heat off without causing overheating and can be worn over a range from 65-95°F. The stretch material provides a sleek fit and has a low density that make them easy to stow away in a jersey pocket.
The Solare fabric features a 4-way stretch polyester that very effectively manages moisture and heat. As you get hotter and warmer, the material allows faster regulation, but when lessened (such as in cooler temperatures) heat is retained to keep you comfortable. Though the weave is tight to effectively block the suns rays, the fabric will allow some airflow. The Arm Skin has an elastic top with silicone gripper inside and out to keep the piece up on the arm, and to hold the jersey in place as well.
As far as lightweight arms sleeves go, the UPF 50 Light Arm Skins from Castelli offer the most effective range and the maximum measured protection. The gripper system works great, and the fabric feels good against the skin. The moderate compression will support and invigorate the arm muscles. Sounds about perfect to us.