Our kids wear both of these brands of baselayers. The first option is slightly thicker, Children’s merino wool layers (code Sowewent10 at checkout) or these are great year round, merino wool layers (SOWEWENT20 at checkout)
Water filter (for larger groups/families) which has a good flow rate but tends to more difficult to fix if it gets a clog but this gravity filter is a little slower but much more reliable to fix by backwashing. If you have a smaller groups we like this filter.