Other sleeping bags on the market require parents to unzip the bottoms of their babies sleeping bag in order to let air circulate so that their babies feet dont become uncomfortably hot. Prince Lionhearts Thermaflow™ technology, fantastic new packaging, quality materials, and competitive price make the Sleep Sacks stand out amongst others currently on the market. * Satin lining and CVC Velour exterior * Satin keeps baby cool in the summer and warm in the winter * Thermaflow™, a patented technology unique to Prince Lionheart, prevents babies feet from overheating and keeping them at the right temperature. * Available in small* and medium (sized according to weight and age of baby) * Available in three colors: beige, pale pink, ice blue * Small size comes with a free night cap in matching color "Studies show that SIDS is least likely to occur when babies sleep on their backs and most likely when sleeping on their tummies. Experts suggest the risk of SIDS for side sleeping may be 2 TIMES that of back sleeping" Dr. William Sears, MD, renowned pediatrician and author