I have several styles of these double wall glasses.  Hard to believe they are glass because they are so lightweight.  But these are the best thermo type glasses I have purchased.  My hot beverages stay hot for the length of the time it takes me to drink them.  I really love that I can set them on my coffee table and not worry about leaving a moisture ring.  There's no condensation with these glasses.  It is worth taking the extra care to handle these delicate glasses, but they are worth it.