Made with 100% recycled fabrics and with biking-specific features modeled after our adult packs, the Moki includes a hydration reservoir and a ventilated, comfortable AirScape backpanel. Sized for kids 4-12 years old Reservoir Included - Osprey Hydraulics LS 1.5 L reservoir with quick access to reservoir Comfortable & Stable Carry - Lightweight EVA foam backpanel creates a comfortable carry and a low profile fit for optimal stability while biking Adjustable sternum strap with safety whistle Stretch mesh side panels on main compartment to accommodate extra layers Item Dimensions: 13H x 8.7W x 5.9D in; Item Weight: 0.77lb