Lionbrand.com info:
Jazz is a delicate looking and surprisingly strong 100% hand-dyed linen yarn.

Gauge:
Knit: variable gauge, recommend size 4-8 (3.5 - 5 mm) needles
Crochet: variable gauge, recommend size E-4 - H-8 (3.5-5 mm) hook

Product Care Instructions: Dry Clean, any solvent. Any dry cleaning solvent other than trichloroethylene may be safely used. Item may not be smoothed or finished with an iron.

Article # 105

The website says that it’s a worsted weight with a variable gauge.