K9 sport sack for dogs size large For Dogs Ranging 4-30 lbs (2-13 kgs) Air 2 Description The Air 2 is the backpack dog carrier people know best. Available in sizes XS-L, it is a durable, breathable mid-level backpack perfect for smaller to medium size dogs. The Air 2 is offered at a reasonable price while including the essential safety and comfort features needed for a comfortable experience. This backpack is recommended for intermediate grade walks, hikes, public trasportation, and bike rides. The Air 2 is constructed with durable Cordura® fabric and form-fitting mesh on the sides for breathability.