When you need more coverage than the Sol Cool™ Long Sleeve Shirt, the Sol Cool™ Half Zip is the right balance between sun protection and freedom. The 4-inch collar is more minimalist than a hood, but zips to the chin to keep your neck from heading to Lobstertown. Mesh on the sides lets the breeze in, and the thumb slots give you that extra coverage. A soft Sol Cool™ fabric lining keeps you and the front zipper on good terms, so don't worry about ruining your chest hair coiffure. Our Sol Cool™ Icefil® knit fabric is embedded with xylitol, derived from white birch trees. When in contact with sweat, xylitol can decrease skin temperature by 5°F, and the Icefil® fabric wicks the moisture to the garment's surface. The same Icefil® treatment blocks UV rays for a UPF 50 rating, giving you more time to enjoy the sun.