Made with brrr Pro fabric for all-day cooling comfort Seam placement avoids high-friction zones, enhancing athletic performance Thumbholes extend sun protection to the tops of your hands Regular fit for casual comfort whether worn alone, under a PFD or as a base layer Slightly dropped rear hem provides additional coverage NRS Men's Silkweight Baja Shirt - Made for more than vacation, the NRS Men's Silkweight Baja Shirt is a summer staple for those who never stop moving. A classic pullover with a high collar and full sleeves for max sun protection plus a quarter-zip for easy ventilation.