Best-selling Ideal Temp is the ONLY swaddle that helps regulate your baby’s temperature. Featuring IntelliThread™ technology, our innovative smart textile absorbs heat, stores it, and then releases it back to your baby, maintaining an ideal temperature and avoiding temperature spikes (that often lead to wakeups). Yes, really. Bonus points: IntelliThread™ fibers are embedded in the fabric, so they won’t ever fade or wash out! The real deal: HALO’s signature 3-way swaddle design easily adjusts to fit your baby’s sleep style: arms in, hands-to-face, or one or both arms out. Includes an inverted zipper for easy diaper changes, as well as scratch-free zipper covers. Its roomy sack design is recognized by the International Hip Dysplasia Institute as promoting healthy hip development. Extra soft, cozy fabric is made of a polyester-rayon blend. Use over regular sleepwear. Ideal Temp is made from a temperature regulating fabric that’s stretchier than standard HALO cotton or microfleece. Because of this stretch, Ideal Temp can run slightly bigger than other swaddles. Make sure to choose the correct size for your baby’s current height and weight rather than having them “grow into it.” We recommend sizing down if between sizes. Condition is preowned - my son wore it for one night before he started rolling and had to be put into a swaddle transition.