This is my 4ply instarsia base teabag hat all sizes patterns. You can use this pattern with ALL instarsia charts. 
 
UK 4ply = US Sports =AU 5ply
 
Sizes
CIRCUMFERENCE
30cm, 34cm, 36cm, 40cm, 44cm, 48cm, 52cm.
Uses the Circumference measurements for most accurate sizing ages approximations are given in the pattern. Note the adult fits me but will stretch to a large head, it will look less slouchy.