Keeps drinks hot for 12 hours or cold for 24 hours. Highest Grade 304 Stainless Steel inside and out. Extra thick 1/2mm outer wall thickness to resist damage. 530ml capacity. Ergonomic Design - fits perfectly into the palm of your hand. Wide mouth design - accepts all ice cubes on the go. Wide mouth allows easy cleaning. Latest 'triple wall' construction - triple insulated. Vacuum installed for ultimate insulation. Intermediate copper layer reflects heat out over from your hand. Environmentally friendly, non-toxic and BPA free.