My new co-worker

This mug is formed by an insulated body with a plastic cap. It will keep a hot drink for 4 hours. (More if you like drinking lukewarm.)
Most of the loss occurs by the plug that it is thick, is not insulated. The opening system is a bit hard, but it has the advantage of being simple which bodes hopefully, good hold over time. The mug is too big for a standard car cup holder, but it fits in the door. Ultimately, this is an elegant and practical object: I'm satisfied with my purchase.