The pattern calls for a “Size U.S. 7 (4.5mm) crochet hook,” which does not exist among standard U.S. crochet hook sizes. (U.S. 7 indicates to me that they are referring to knitting needle sizes, not crochet hooks.) 4.5mm falls between Size G (4.25mm) and H (5.00mm). I used a G hook to make sure that the fabric is tight enough to not have holes. Between my choice of hook size and the fact that I am a tight crocheter, the finished mittens are much closer to what would fit a 2-year old than a 4-year old. Since these mittens were destined for a charity that had requested children’s mittens in an assortment of sizes I was not concerned with the exact finished size that I obtained.