These two 100% cotton yarns are very different, but knit up great together in our free Crayon Stripes Pullover pattern! Cotton Pure is made with 100% organically grown unmercerized cotton spun in a multi-ply structure, making it smooth and supple with an appealing matte finish. On the other hand, Serif is 100% Peruvian Pima cotton and is a single ply of cotton wrapped with a thin cotton thread, a structure that makes this yarn lightweight, textured, and unbelievably soft. Knitting stripes of each is an amazing way to feel the difference!