Made of acrylic. These are oversized! I wear an XS in this sweater but my normal EU size is 36/Medium. See measurements below.
 
Measurements
XS: Chest 54 cm across front when lain flat. Length 60 cm
Small: Chest 56 cm across front when lain flat. Length 62 cm
Medium: Chest 58 cm across front when lain flat. Length 64 cm