LET’S DRINK TO THIS! Boon SNUG Silicone Straw Sippy Lids stretch easily over the included cup or any regular cup with a diameter 2.5–3.75 inches to turn it into a straw sippy cup. The lid instantly helps prevent the cup from spewing its contents when knocked over or tossed off of a high chair. Boon sippy lids with straws are great for kids who've outgrown their baby cup and are old enough to drink from a straw cup, but not quite ready for an open cup. The sippy cup and sippy cup accessories are top rack dishwasher safe, making it easy to clean away all the goo.