Smooth Wall flexible liners are more than twice as thick as the standard corrugated liners, .013 vs. .006, and are 2 ply liners vs. the single ply, standard corrugated liner. The construction of the Smooth Wall liner is unique since the inner ply liner has a smooth surface, allowing it to vent up to 20% more BTU's for gas burning appliances and 15% more gallons per hour (GPH) for oil burning appliances. By being able to vent up to 20% more BTU's or GPH, the Smooth Wall Liner will sometimes allow you to downsize the liner diameter when venting a gas or oil appliance, making an easier installation or to accommodate a tight chimney flue and still giving you the correct amount of BTU's.The material difference between the Smooth Wall liner and the corrugated liner is the grade of stainless steel. The Smooth Wall liner is made from 316L stainless steel, whereas most corrugated liners are made out of 316ti stainless, which is the "Best" in the industry. Although you can find some that are only 304 stainless and .005 thick. A small amount of titanium adds a lot of quality to your liner. The difference between the 316L and 316ti is the titanium that is added allows it to maintain higher temperature and mechanical strength, for longer periods of time.Both stainless liners are easy to clean, and the creosote will not penetrate them as it is does with the older clay tile flues. Smooth Wall liners clean off easily using the nylon hard bristle brush as do the corrugated liners. In addition, because of the heating and cooling of the corrugated liner, it expands and contracts, knocking off particles of creosote that may have collected in the corrugations.There are real benefits to the corrugated flex liners, they have the ability to be reshaped into oval, square, or rectangle shapes, depending on the application needed. This becomes important when installing a round liner through your fireplace throat damper, it can be shaped to fit through and connect to your stove or insert. The Smooth Wall liner should not be reshaped, doing so will change the inner smooth wall surface, causing turbulence in the air flow which reduces the draft.