When you need something that is between a sippy cup and a regular tumbler, containers with a built in straw are a good choice. I originally bought these when my youngest was going through a "drop everything" phase. The straw is built in to the lid so when you turn it, the straw retracts. That reduces the amount of liquid that can leak out but it doesn't claim to be 'leak proof'. I never had any of the cups or lids break or crack but I did have to replace the lids because the straws wouldn't completely retract. When you screw the lids on make sure that it's even, if it isn't threaded correctly then you are going to have leaks. The lids can be used with other tumbler sized drink containers from Gerber so if you like the retractable straw feature you can use these with other containers. I like the idea of having a built in straw but I wish that the design was a little better. If you have kids that like to drink out of a straw instead of a tumbler this is a good pick but make sure you know where to buy the replacement lids.