I bought these booties in Sky Blue in December for my then 3 month old.  He's still wearing them into his 7th month (unless his dad lost one today - oops!).  I love how they are easy to get on, but he can't kick them off easily.  The adjustable sizing is wonderful and a big $$ saver.  They do get dirty easily, but you can throw them in the wash with the rest of your laundry and they come out good as new.  One other thing - these aren't meant to be worn outside in the freezing cold for long periods of time.  When it's that cold out the baby should be indoors anyway!