Outdoor Research Men's Sentinel L/S Shirt 85% polyester/15% cotton; EPA-registered Insect Shield Imported Relaxed fit with curved hem drirelease cotton; 85% polyester/15% cotton fabric provides comfort and moisture management; UPF 20 Insect Shield clothing repels mosquitoes, ticks, ants, flies, chiggers and no-see-ums for ultimate insect protection Insect Shield is odorless, safe, and EPA-registered; lasts the lifetime of the product (over 70 washes) Front button closure