Paul W.wrote a review of Castelli Lycra Arm Warmers on October 7, 2009
The white arm sleeves are just right to keep the sun from burning your arms mid-day. They are not noticeably warm on a hot day, yet do provide some warmth on a cool day. Also good for around town motorbike use, and other packable layering applications.
At first the medium size seemed too tight on the upper arm, but after a few rides they are a good fit and don't slip.