Ordered the 6-9m red version for my 8 month old.  She wore it hiking on a sunny day.  I was worried about her overheating in the long sleeves, but that didn't happen.  She was happy and comfortable all day which meant less sunscreen to spread.  Hooray! Fabric isn't very stretchy, super breathable though.  She'll get too big for it soon, so I don't agree about the suits being sized big.  Simple but still cute and as effective as it claims to be.