A "swaddle sack" is a special kind of baby blanket or sleeping bag that is designed to wrap around a baby snugly, keeping them secure and cozy. It helps babies feel safe and comfortable, similar to being held in someone's arms. Full definition
There are alternative swaddle blankets, like swaddle sacks from Halo or SwaddleMe that works great for bigger babies and are able to securely keep infants swaddle in a safe manner. (bestswaddleblanket.com)
If that doesn't work, then using swaddling sacks will hold newborns in a tight burrito because they have tighter restraints with zippers and Velcro systems. (bestswaddleblanket.com)