Stone Island Half Zip Knit in Black. Crafted from a high-quality lambswool blend in a Stockinette stitch, the Half Zip Knit from Stone Island is a great addition to any winter wardrobe. Featuring a hidden zip under the four-button closure, this piece has the functionality of a half zip with a contemporary take on the smart/casual staple. Designed with ribbed cuffs, collar and bottom band for a great fit no matter what the outfit.