Lang Yarns Donegal Tweed+ knitting yarn is a pure wool yarn made in the true Irish tradition, knits on knitting needles 4.5 and 5 mm for a gauge of 17 stitches and 25 rows.
In a 50 gram ball there are about 105 meters (114 yd) so to knit a sweater plan on:
600g = 12 balls for men size M
450g = 9 balls for women size M
350g = 7 balls for children 10 yrs
Hand wash with detergent for wool without fabric softener.