Rubie's Official Marvel Avengers Endgame Captain America Classic Childs Costume, Kids Superhero Fancy Dress

What size will fit 8 years old

Can anyone tell me what the mask is like at the back? Is it just an elastic strap or does the mask material go all the way round?

Witch size is best for a 10 year old

My son is 106.68 cm tall should i go for small size?