Mario Andretti wears this underneath his race suit. We're pretty sure.
*UNISEX*
• Sport Grey is 90% cotton, 10% polyester
• Classic fit with long sleeves and rib cuffs
• Pre-shrunk jersey knit
• Seamless double-needle 7⁄8'' (2.2 cm) collar
• Double-needle bottom hem
• Taped neck and shoulders
• Quarter-turned to avoid crease down the middle