These socks fit really well on my 6 lb 11 oz newborn.  She's still wearing them now at 10 lbs 10 oz.  They stay on her feet well and are thick enough to keep her toes nice and warm.  The wash bag is definitely a throw-away; it just opens in the washing machine and the socks fall out.  I wash them in a zippered laundry bag to keep them from getting lost.