You should choose the correct size sleep bag/sleep suit based on your baby’s height, not their age.

The LOVE TO DREAM SLEEP BAG™ is available in 2 sizes:
Size 0 - 6-18 months (suitable for maximum child height of 88cm)
Size 1 - 18-36 months (suitable for maximum child height of 108cm).

The LOVE TO DREAM SLEEP SUIT™ is available in 5 sizes:
Size 0 - 6-12 months (suitable for maximum child height of 84cm)
Size 1 - 12-24 months (suitable for maximum child height of 92cm).
Size 2 - 24-36 months (suitable for maximum child height of 100cm).
Size 3 – 3 years (suitable for maximum child height of 108cm).
Size 4 – 4 years (suitable for maximum child height of 115cm).