The Super Soft Baby Sleeping Bag Comforts And Grows With Baby During And After The Swaddling Stage. It Is Made From 100% Soft Breathable Cotton And Is Acknowledged By The International Hip Dysplasia Institute For Its Design Which Swaddles To Waistline For A Hip-Healthy Natural Leg Position. • 0 To 3 Months - It'S A Snug Swaddle, Which Cocoons Your Baby And Helps To Prevent Startle Reflex. It Is Easy To Swaddle Your Baby With Arms Tucked In For Total Snugness Or Arms Out. • 3 To 6 Months - It Transitions To A Cosy Sleep Bag. Unclick The Poppers To Free Your Baby’S Arms And Hands To Allow Them To Self Soothe • 6 Months Plus - Their Favorite Sleep Bag Becomes A Romper. Simply Open The Poppers At The Bottom And Baby Is Free To Stand Up And Move About. The 1 Tog Nite Nite Romper &Amp; Sleeping Bag Also Has A 2-Way Zip For Easy Changing, A Chin Guard And Safe Open/Close Clickable Poppers And Has A Tog Rating Of 1 For Warmer Nights Designed To Make It Natural For Baby To Move From Swaddles To A Sleeping Bag. It Helps Your Baby To Stay Active And Allows Freedom To Move Around, While Enjoying The Comfort.