My daughter is 21 months old. I bought a Bell brand helmet at Target for toddlers and it was way too big. Her 4 yr old big brother has a Giro helmet that has an adjustable dial for head size at the back of the helmet, so I searched on-line for Giro helmets, knowing this is what I needed for my daughter's little head. My son has worn his since he was 2 and it still fits at age 4 and still has growing room (he does have an average to bigger sized head). Easy to adjust with dial and straps. I love the bunnies and pink for little girls. I would recommend this as a child's 1st helmet and one that they can wear for several years. Worth the money.