Heat-Treated! The "bumpers" near the bottom of the glass help prevent rim to rim contact, extending the service life of the glass. Cascade glassware features the Safedge® Rim Lifetime Guarantee. If the rim of any Safedge® item chips, Libbey guarantees to replace or refund the price of the glass. Perfect for quick service restaurants, Cascade features a unique optic design with "bumpers" near the bottom to prevent damaging rim to rim contact.