What's the most important factor when buying junior bindings?

Fit is paramount — the binding must properly secure the child's current snowboard boot with the heel seated firmly in the cup and straps applying even pressure without bottoming out or leaving excessive slack. A poorly fitting binding is both a safety hazard and a barrier to learning. After fit, smooth ratchet operation is the next priority, as sticky ratchets frustrate kids disproportionately. Flex should be soft (1–4) for most youth riders, and cost should be reasonable given the short ownership period.