The BreathableBaby BreathableSack Wearable Blanket Size Medium runs from 6 to 12 months (16-24lbs). The Breathable Sack uses a performance fabric that includes wicking technology. The result is that your baby remains dryer and more comfortable. In addition, this soft fabric is perfect for all-seasons. The Breathable wicking material removes moisture up to 10X better than other brands. It also helps prevent Overheating, a risk factor for SIDS. BreathableBaby Breathable Sack Wearable Blanket in Aqua/Gray Chevron. Size Medium.