There is a good assortment of sizes. I had no problem with attaching or removing the lids. They do seal well and the containers have a lipped edge for the lids to better secure to the containers. The containers are lighter than what I thought they would be. I don't know if that will mean they will be less durable yet. The lids locking tabs are made of a thicker plastic and I can foresee them lasting awhile before repetitive usage will break them. These containers will come in handy and with features like being leak proof, air tight and eco friendly. It is better than plastic containers.