Our daughter is very tall, so we had to stop using blankets to swaddle her when she was about 2 weeks old.  We tried having her sleep in just a sleeper, but she would frequently wake herself up.  We ordered this swaddle sack as well as the Disney Princess sack, both in Newborn size.  This sack was visibly smaller than the other one, so they must have changed their sizing at some point.  We used this one first until she outgrew it length-wise (around 1 month), and then were able to use the Princess sack until she outgrew it at 2.5 months.

It survived quite a few washings but I was disappointed that both sacks showed signs of the threads pulling out where the Velcro straps attach at the very first washing despite being washed on "delicate" and air-dried.  That's the only reason I'm giving it four stars instead of five -- it looked quite old and used after the first wash because of the threads, but it did hold up very well.