Fourlaps Level Tech Half-Zip is engineered to provide top performance through the toughest conditions. The secret 37.5™ technology uses active particles to vent heat in warm conditions and retain it if it's cold. This tech is proven to increase your body's efficiency by up to 26% at lactate threshold, so you can push yourself firther than you've ever gone before. 
 
Features: 
Athletic fit 
Zippered neck with reflective tape 
Super-soft fabric 
Powered by 37.5™ technology 
Anti-microbial 
Reflective tape on hem for high visbility
Reflective "4" logo on back 
 
Fit: 
Small - Chest 34"-36"
Medium - Chest 37"-39"
Large - Chest 40"-42"