Redundant Air System With Pony Bottle and Free Tank Mount Bag by H2o Odyssey comes with the new environmentally sealed -RG3V balanced diaphragm first 1st stage with on/off valve -2nd stage connects via a vertical/horizontal swivel -Availible in kits which include:- 1st & 2nd stage- 13 (standard) or 19 cubic foot tank (For an Additional $29.95) - Station Filler. Now you will have plenty of air in an emergency and you can rest assured that your back up air will be ready when you need it. Free shipping does not apply to this one, sorry.