First of all – the BISTRO storage jars are adapting to the needs of their content – the knob on the lid of the jars gradually adjusts the airflow from completely airtight to breathable, making them the perfect fit for just about any storage need. Second – they are rectangular in shape as not to leave any dead space in the fridge. And third – the middle of the lid is transparent so the jars can be stored in drawers without having to lift every single container up to check its side. They’re made from plastic, silicone and stainless steel and come in three different sizes.