Volere Double Walled Mug 11-Ounce, Set of 2

Despite high expectations, one of the four cracked in the second week, another has an internal wall crack, a third just came out of the dishwasher with a rough lip. The fourth has remain unscathed. I understood the risk - after all, they're made of glass - but so soon? They've been either hand-washed gently and air-dried or run through the dishwasher. Color me confused.

lightweight, yet durable and solid feel to them... ergonomically, well placed handle... the double wall keeps coffee or tea warm longer and outside of mug is cool to touch... well done! Thank you!