We took our premium bodysuits to the next level by using cotton interlock fabric instead of our tried and true, comfy classic, cotton rib. Cotton interlock is extremely soft, warmer than cotton rib, and holds the perfect amount of stretch, making it perfect for baby clothes. We had our essentials independently certified with STANDARD 100 by OEKO-TEX® so that you don’t have to worry about harmful substances in your baby’s clothing.