Use any aran weight yarn. I just like Galway and have used it twice. This is a great choice to make as a gift for Dad. It’s classic style is never out of fashion. The borders are in an easy mock cable rib, so it looks a bit better than completely plain. The armholes are generous to accomodate full sleeves at: 9 (9 1/2, 10, 10 1/2, 11, 11 1/2) ins. Length to back of neck is: 25 (26, 27, 28, 29, 30) ins. Choose a size approx 2-4 ins bigger than chest measurement.