Featuring Nuna's 3D growth system™, the Aace booster is a safe and adjustable car seat that adapts to your growing child. Height adjustable headrest. Expandable shoulder system. Adjustable seat depth. High-back and no-back positions. Side impact protection pods. Reclinable seat. Built-in arm rests. Ventilated panels. High-back booster suitable from 40-110 lbs. No-back booster suitable from 50-120 lbs. Highest position: 22.5"W x 15"L x 33"H.Lowest position: 21.5"W x 26"H.15.6 lbs. Polyester. Plastic. Machine wash fabrics. Imported.