Horizon Organic is moving into single-serve territory with the help of Tetra Pak’s Prisma 8-oz aseptic drink carton. Designed for those on-the-go, Horizon’s ultra-pasteurized organic milks in four flavors are now available in supermarkets and natural foods stores across the U.S. and in the U.K. Available in two-percent, reduced fat, plain and three flavors–vanilla, chocolate and strawberry–each drink box costs about $1.