These bottles are designed for storage of solutions and are ideal for media preparation. The 9.5L (2.5 gallon) and 13.25L (3.5 gallon) sizes are in a conventional bottle shape. The 19L (5 gallon) and 45.5L (12 gallon) sizes are similar in design to a carboy. The 19L size is weight controlled to 15 lbs maximum for ease of handling. The necks are tooled to increase mechanical strength and for uniform stopper fit.