At first, I wasn’t sure what these sacks were meant to be used for. After some research, I realized it was made to be a safe alternative to blankets to keep baby warm. From what I read, it’s not safe to keep blankets, pillows, and toys inside the crib as they can pose as a suffocation hazard. It’s also important that you have the proper fit as well – the neck opening should not be able to go over the baby’s face.
With that being said – these are the sleep sacks that caught my eye! I find that Perlimpinpin has a larger variety of prints that you can choose from. They also have a variety of fabrics to choose from, such as: cotton, muslin, bamboo.
Meanwhile, Kyte Baby has a good selection of simple colored sleep sacks. They have a beautiful variety of colors and each color can be purchased with the TOG rating of your choice. You can read more about that here. They also have patterns to choose from, but I think the single colored sleep sacks look better. Oh and Kyte Baby gets bonus points for incorporating a double ended zipper.