Scientifically designed for self-soothing and sounder sleep. The gently weighted Zen Sleep Sack helps your baby sleep through every sleep phase. Designed to help babies self-soothe and learn to fall asleep independently, the Zen Sack eases the transition from swaddle to sack, and prevents sleep regressions and disruptions: "A sleep training essential". Features: ▪ Two-way zipper makes diaper changes a breeze ▪ Zipper covers, cuddly seams and soft tags protect your baby’s skin ▪ Can be worn backwards by tummy sleepers who can roll independently ▪ Grow-with me adjustable snaps ▪ 2.5 TOG Cozy for added warmth Safety: ▪ Mimics your reassuring palm and calms with only a few ounces ▪ Applies gentle pressure that is tested for breathing safety ▪ Adheres to all known CPSC safety requirements ▪ Tested for suffocation hazard, pulmonologist verified ▪ Hip-healthy. Does not hinder mobility ▪ The safer alternative to all-weighted blankets