Errata from raveler FWknits:
Hat – shape top size 1. Amend row 12 so that it reads:
12th row P2 tog, p4, rep from to end. 45 sts.

Part of a two-piece set: “Snowflake Hat and Scarf”
For the scarf pattern see Snowflake Scarf

Yarn requirements for hat and scarf combined
2 balls each of two colors of Jaeger Matchmaker Merino DK (130 yd/ball)

No measurements are given.