The mugs of the KF4041 coffee mug set by Kaffe have a timeless, classic design with the benefit of high-tech tempered glass. Our double-walled glass construction is functional with superior heat-retention, but with its clean, modern lines, it is also truly elegant and a beautiful surprise for guests. Coffee connoisseurs, or anyone serious about handcrafted coffee, will love this premium-quality coffee mug set. The superior materials mean lasting performance: Borosilicate glass is tempered for strength, making it crack-resistant and shock-resistant. Bring sleek, modern elegance into your home with this beautiful blend of form and function. Recommended for use with the Kaffe KF1010 French press which is made of the same durable, double-walled borosilicate glass.