From the seller

Toddlers and messes go hand in hand, but you can eliminate at least one kind of leak with Munchkin's Click Lock sippy cups, which come with a 100% leak-proof guarantee! These innovative toddler cups have flipping straws and feature a simple locking lid that closes to create a leak-proof seal. You can see, hear and feel the cup lock in place, so you have triple assurance against dribbles and drips. Munchkin even backs this no-leak promise with a 100% replacement guarantee. Secured, and rest assured - this might just be the sippy cup of your dreams. Some things in life just CLICK! Leak-proof toddler cup with a flip-top lid and flexible, silicone straw No room for error - Click Lock Technology locks lid in place with an audible click 100% leak-proof guarantee Soft, silicone leak-proof straw flips up and out when ready to drink 266ml capacity for water, milk or juice BPA-free & Top rack dishwasher safe 12+ months