FITS has introduced the Sarah half-zip shirt for cooler weather riding, which emulates the sensation of skin against skin. The Sarah shirt acts as an insulator, yet can stretch to fit most body types. The shirt is made from natural fiber and features flat seams and a reverse tape zipper design to reduce chafing. Sarah is offered in black, stone, red and steel and comes in XS, SM, MED, LRG and XL. The shirt costs $64.
Check out http://fitsriding.com/shirts_sarah.php for more details.