Any yarn weight is suitable for this pattern.

Scarf A was made with a No. 1 Superfine yarn (fingering / 3ply).

Scarf B was made with a No. 3 Light yarn (worsted / DK).

A heavier weight yarn will work up faster with less rows than a
light weight yarn.

Hook Size (as in indicated on label on chosen yarn)
4mm / US G6: Hobbii Unicorn
3.5mm / US G4: Scheepjes Catona
5mm / US H8: Hobbii Hurricane

Other materials:
Scissors, blunt needle, stitch markers x3 and a measuring tape.
Gauge
Materials
Abreviations & Terminology
US Terminology

Gauge is not important for this scarf: the scarf is crocheted until the the rows reach the required measurements (indicated in the pattern).