The baby size, ideal for average children ages 6 months to 36 months, measures approximately 10.75 inches or 27 cm from top to bottom, and 8.5 inches or 21.5 cm from side to side. The circumference of the neck is approximately 11 inches or 28 cm when adjusted to the largest size. The Toddler size, ideal for average children ages 1 year to 4 years old, measures approximately 12.5 inches or 31.5 cm from top to bottom and 9 inches or 23 cm from side to side. The circumference of the neck is approximately 13 inches or 33 cm when adjusted to the largest size.