This tumbler is a bio-composite of 70% bamboo fibers and other natural materials. Bamboo is a fast-growing plant that thrives without fertilizer or pesticides, making it the perfect resource to harvest again and again. Stainless steel interior and push on lid for added hot and cold retention. Base of tumbler features nonslip grip for extra stability. Dishwasher safe (top rack only), hand wash recommended. Color and pattern variances are to be expected.