From the Knit Rowan website:
Knit this chunky pull on accessory hat from Warm & Toasty, a design by Gemma Atkinson using Tumble, a glorious lightweight, soft and lofty yarn (alpaca and cotton). With garter stitch detail, this knitting pattern is suitable for beginners.

Finished dimensions:
To fit head circumference of an average woman.

Yarn Information:
Photographed in Pine Needle 571
1 skein
77 yards