Libbey’s exclusive DuraTuff® treatment increases resistance to thermal shock (sudden change in temperature) and mechanical impact (sudden impact with another object). This special thermal after-process for ‘pressed’ tumblers and stemware strengthens the upper portion of the glass, the area most vulnerable to breakage. It results in remarkably durable glassware with prolonged service life. Improper stacking shortens the service life of glassware. Pyramiding is the best method of storage to minimize wear. If you do stack glassware, select glasses that are designed to stack to extend service life and reduce replacement cost. If the rim of any glass covered by the Safedge guarantee chips, Libbey will replace or refund the price of the glass when it is returned to the dealer from whom it was originally purchased. Of course, this guarantee does not cover breakage. Libbey’s Sheer-Rim Dura Temp Edge stemware and tumblers feature a beadless edge that is first cracked off then polished to produce a fine, yet durable edge. This creates a combination of elegance and affordability in glassware for operators looking to upgrade their beverage service, while still maintaining longer service life. Sheer-Rim D.T.E. tumblers and stemware are guaranteed against chippage of the rim.