Nuk Fun Grips Spill Proof Cups Nuk Fun Grips Spill Proof Cups are fun, colorful cups that change color when cold fluids are poured into them, and as the fluid temperature goes up with the warmth of hands, the color transforms yet again. They're fun to observe and joy to sip from. They come with interchangeable lids. Why You'll Love It: These cups are easy to handle and clean, and kids will like the magnificent color transformations. Features Spill-proof Color changes when temperature of contents changes Unique shape for better grip and control Dishwasher-safe