Hartwick Roadside Insulated Tumbler

Proof that vacuum insulation is a solved problem at a fair price. The Roadside is a 470 ml double-wall stainless tumbler with a press-fit sliding lid, and it keeps coffee hot for three to four hours — the same physics as tumblers costing three times more, because a vacuum gap is a vacuum gap. Where the savings show: the lid is splash-resistant, not leakproof, and the powder coat is a single utilitarian green rather than a seasonal palette. Where they do not: the 18/8 steel interior takes no flavors, the base fits cup holders, and the seams are welded, not glued. Hand-wash the body, top-rack the lid. If you lose travel mugs the way most of us do, buy this one twice.