FEATURES of the Arcteryx Men's Accelero Comp Short Sleeve Durable, smooth knit front panel reduces chafing Mesh back increases ventilation and comfort in hot weather; treated with anti-odour and wicking finish Strategic flatlock construction reduces chafing Reflective blades and logo for low light visibility Provides sun protection (UPF 50 (front)) SPECIFICATIONS of the Arcteryx Men's Accelero Comp Short Sleeve Weight: 140ml / 135 g Fit: Athletic Helius - 100% polyester Viente - 100% polyester ARC'TERYX ATHLETIC FIT: The Arc'teryx Athletic Fit garments are considered their "standard" fit and feature complex patterns that utilise anatomical shaping and gussets to enhance motion and eliminate any excess bulk. Athletic fit styles are trimmer than Arc'teryx relaxed fit styles, but still offer room for a base layer, a light fleece mid-layer, and a synthetic or down filled mid-layer. Put simply, their Athletic Fit should fit true to size, but be sure to cheque out the size guide to learn how to calculate your body measurements before selecting a size. This product can only be shipped within the United States. Please don't hate us.