The KB EuroPro Skull cap is the a great way to gegulate your temperature and keep sweat out of eyes.  Constructed of a lightweight, perforated, Quick Wik fabric, the super thin skull cap fits easily under your helmet.  

These light weight breathable skull caps will minimize the cooling effect that wind can have on wet hair and moderate the swings created as you head heats up and cools down through your work out.  In addition, the brim of each cap has a micro-fiber abosbant lining to further wick moisture away from your eyes.

The caps come in three sizes:

Small for heads 18" to 22" around

Medium for heads 20" to 24" around

Large for heads 23" to 26" around