This pattern uses Fleece Artist’s new Halo Bundle yarn, which is really 2 separate yarns--Merino Slim and Angel Hair--that are dyed together. When knit together, the two fine yarns knit to a worsted gauge. The size adjustment is made by changing needle sizes, so the gauge is slightly different depending on what size is being made. The 18” size was knit on size 4 circulars for the brim and size 6 for the body of the hat. Changing to size 5 for the brim and size 7 for the body will yield a 20” hat. The hat is stretchy and slouchy, the kind of hat you want when you don’t want to mess your hair. This is a quick and easy knit.