Use to protect skin from sun on long rides. Have worn with temps in high 80's and they're surprisingly comfortable. Slightly tacky lining on top keeps them up inside your shorts. Liked my first pair so much I bought another three.
This is a great cap for warmer weather. I love it because it does a good job of absorbing sweat on hot rides, without being thick or bulky underneath a helmet. The fabric is soft and comfortable. I also use it for trail running in as a sort of sweat band with a little sun protection.
My 10-year-old Campy full fingered gloves started coming apart this winter so I looked for something similar. I like Castelli's CDS pad layout (I have a couple pair of their Corsa Rossa gloves) so the Perfetto looked promising. I've worn them on every ride except one unusually warm day since Christmas. Every Castelli apparel I have is sized large (I'm 5'9, 160 pounds) where in US companies (e.g., PI, Hincapie) I take a medium. On one hand, I'm looking forward to a warmer Spring where I can shed a layer and get back to half-finger gloves. On the other hand, the Perfetto's are great. I hope they last as long as my old Campy's.