Deep Draw Liner - The Starline Advantage 

The majority of Starline’s vacuum mugs have a deep draw liner. That means the liner is created using 1 piece of steel that does not require it to be cut or welded together. The stainless steel is forced through a die and stretched into shape without causing excessive wrinkling, thinning or fracturing of the material. 

A continuous metal will hold the vacuum better than a welded liner. If there is a weld, depending on the quality of this weld, there is a strong potential that eventually the weld will weaken and allow some of the vacuum to escape.

In order to make a liner using the deep draw method, better quality stainless steel is required for the manufacturing process to ensure it does not fracture while being stretched into the mold cavity.