About the Product: These very lightweight clear double walled mouth blown glass mugs are beautiful and delicate, yet sturdy. Constructed with borosilicate glass they are resistant to thermal shock (quick change in temperature from cold to hot or vice versa) and are dishwasher and microwave safe. Note that the sizes given reflect liquid filled to the brim of the cup, so in the ten-ounce size eight ounces is held comfortably. - Amazon Customer You Name It You can call this item coffee mugs, cool mugs, mug sets or mugs set, the point is it gets the job done! Money Back Guarantee: If you are not 100% happy with your "Double Wall Mug Glasses" by Home fashions, simply return the product to Amazon for a full refund because that is how confident we are you will LOVE our Double Wall Mug Glasses!