SUPERIOR COMPRESSION: Our mens short sleeve compression shirt delivers powerful compression to shoulder, chest, back, & abs for max athletic performance. Shirt is lightweight, comfortable, supportive. 4-WAY STRETCH FABRIC: Athletic shirt features nylon spandex fabric for maximum mobility & comfort. Breathable, sweat wicking fabric keeps you dry throughout your workout or training session. BASE LAYER SHIRT: Provides added insulation and protection when worn as an undershirt during gym workouts or outdoor activities. Underarm mesh vents keep you dry, cool, and comfortable during exercise. DESIGNED FOR ATHLETES: Compression shirts are loved by athletes worldwide for running, lifting weights, football, baseball, cycling, and more. Optimal muscle support helps you get more from workouts. TRUSTED QUALITY & SATISFACTION: CompressionZ's thermal under shirt is backed by superior quality. For a more relaxed fit, we suggest ordering one size up than what's suggested in our size chart.