Columbia Men's Midweight Ii Long Sleeve Top 100% Polyester Imported Machine Wash Zoned thermal-reflective technology at front and back torso and breathable, sweat-wicking side inserts give you what you need, where you need it, while a versatile midweight fabric lets you wear this comfy long sleeve baselayer top in a wide variety of conditions and situations Flat-lock seams slide smoothly over your skin and underarm gussets deliver great mobility