Grobag Baby Sleep Bags are the safer alternative to top sheets and blankets. Grobag is FSID's (The UK's leading crib death research charity) only recommended baby sleep bag. An ideal time to start using a grobag baby sleeping bag is when your baby weighs more than 8.5 pounds (0-6 months size). It is very important to check that your baby's head cannot pass through the neck-hole when the grobag baby sleeping bag is fastened for use. Please remember that these are recommendations only as all babies are different. Size: 0-6 months minimum child weight 8.5 pounds; max child length 27"; 6-18 months: minimum child weight 18 pounds; max child length 34"; 18-36 months: minimum child weight 25 pounds; max child length 39". Choosing a Tog: A tog measurement is a European warmth rating based on the thickness of the bag: the higher the tog, the warmer the product. Grobag baby sleeping bags are available in two tog ratings. Tog 2.5 for standard room temperatures of 61-68 degree Fahrenheit, Tog 1.0 for warmer weather and in rooms of 69-73 degree Fahrenheit.