The Oliver fingerless gloves are designed based on craft yarn council guidelines, as measured around the four finger knuckles:

Small: 8”
Medium: 8.5”
Large:9”

You will need worsted weight yarn (70-90y main color, 20-30y contrast color) and a size H crochet hook. The gloves are worked bottom up, beginning with the ribbing. You will need to know how to do front loop only and back loop only single crochet, chain, and slip stitch.