Do MontiiCo bottles and cups have a liner?

No. All MontiiCo products are made from high quality, 18/8, food-grade stainless steel. Stainless steel is naturally free of BPA and other harmful substances.
Stainless steel is inherently safe for food and beverage contact; plastic or epoxy linings are not necessary. This is one of the main differences between a stainless steel MontiiCo and aluminum bottles. All aluminum bottles must have a liner to maintain the integrity of the contents inside the bottle; otherwise, the aluminum leaches into the contents, which is unsafe.