The Helmet Kids Want To Wear! Adjustable Fit Custom dial is a quick, easy and effective adjustment system Lightweight In-Mold Shell design keeps the weight down for less stress on their young bodies. REF: 391618 Kids like a helmet that doesn&';t weigh them down. So we built the Grom, a superlight junior helmet with custom dial adjustment system that fits every head shape. WEIGHT: 0.32KG SIZE RUN: [KS 49-53cm , KM 53-56cm]