As stated by Dreamland Baby, the weighted sleep sack is designed to help baby feel calm, fall asleep faster, and stay asleep longer. The gentle weight naturally reduces stress and increases relaxation through deep-pressure stimulation to give baby feelings of security and comfort - just like a hug! 

The weight is located on the front (or top) of the sack only, and will not restrict movement, so your baby can safely roll, sit or stand!