The sweater is worked with double yarn in four different shades.
150 (350) 400 (525) g natural black
50 (50) 50 (50) g grey
50 (100) 100 (100) g light grey
25 (100) 100 (125) g dark grey

The photo shows a modified version of the pattern, worked in a smaller size with a finer yarn and excluding some design elements. The sheep and their placement on the yoke are the same though.