double-wall construction keeps your drinks warmer longer, and protects hands from hot contents. great for beverages on the go. hand painted reactive glaze on stoneware. reactive glaze creates a cat-eye jewel effect with pools of glaze reflecting light. made by artisans, each piece has unique, variegated reactive gaze in muted, subtle colorations, created through reactions of the clay, the glaze and heat in the kiln. no two are alike.