This hat was designed and hand-knitted by me and features a fun snail design. Sizing and measurements: When it lays flat, this hat is about 8in tall and has an opening circumference of about 18in. It will stretch to fit the wearer’s head when worn and will fit most heads normally. About the yarn: This yarn is Knit Picks Wool of the Andes Worsted. It is 100% wool.