The stylish Ichimatsu Collection mugs are equipped with high quality double wall stainless steel vacuum insulation construction that keeps beverages hot or cold for hours. Stainless steel vacuum insulation keeps beverages hot or cold for hours. The twist-off lid makes the drinking experience more like drinking from a regular cup. ompact lid design has fewer parts for easy cleaning. 2-step method for disassembly and reassembly of lid ensures no accidental leaks, and helps prevent the loss of parts. A special manufacturing technique was used to round the bottle opening, making it smooth and comfortable to the touch when drinking and cleaning. 1-5/8" (4cm) wide mouth opening accommodates full-size ice cubes, and is easy to fill. Easy-to-clean double layer nonstick coated interior enhances durability, and provides greater protection of the stainless steel against salt-containing beverages like sports drinks. Made of BPA-free plastic and 18/8 stainless steel. The lids are interchangeable with SM-TAE48, allowing for a wide choice of color combinations and use. "Ichimatsu" is a two-toned checkerboard pattern that holds historical significance and recognition in Japanese culture. In the mid-Edo period, a popular Kabuki actor named Sanogawa Ichimatsu was known for wearing pants with this pattern.