These are brilliant. Leak proof completely air tight which means that your fruits and salads actually stays fresh. I tested the leak proof aspect and it works. The lid features a new locking design which is designed to give you a double locking system. The rubber is thicker than the standard product on the market. The glass is oven safe and microwave safe without the lid’s. These are also dishwasher safe. Always put the lid on the top rack. The variety of size ensures you will have the one you need for the task at hand.