This cowl pattern is knit in the round on US size 15 (10mm) circular needles or DPNs for the adult size and US size 10 (6mm) circular needles or DPNs for the child size.
Chunkier or finer yarn can easily be substituted but you would need to adjust your stitch count up or down accordingly.
The icord edging gives the pattern a lovely finish, for more adventurous knitters.