FEATURES OF SISTEMA KLIP-IT CONTAINERS>> Absolute seal--achieved by "O-rings">> Easy to open/close. You do not have to press the containers closed nor pry them open. Just place lid on top and "latch" closed, or unlatch and lift the lid off.>> The sides of most are nearly vertical, not inclined. So, you can't stack the bottoms inside one another. But that also means that there is no wasted space.>> For all practical purposes, you must store them with the lids on. But that also means you don't have to hunt for the lids. Containers of the same size stack well on top of one-another, and those with the same size top stack well.>> The top adds another 3/8" or so of usable space, so you can fill the containers "to the brim".CAUTION>> While the Sistema containers are nominally "dishwasher safe", any plastic can be damaged by the heating coils in your dishwasher. I learned this because my current Bosch dishwasher doesn't have a "drying" cycle, the metal pots and ceramics dishes dry from the heat they absorb from the washwater. The plastic doesn't dry at all---but it also remains undamaged, compared to my Frigidaire dishwasher which regularly damaged my plastic storage containers. Several other reviewers report that dishwashing the Sistema lids causes them to distort, and for the blue lock clips to become brittle and break. So, if you want your Sistema containers to last, either hand-wash them, or turn off the "dry" cycle of your dishwasher (or choose a cycle which "air dries"). You'll also save a lot of electricity ($$$).>> While the Sistema containers are nominally "microwave safe", any plastic can be damaged by overheating---especially the tops which can warp. While you can CAREFULLY warm up cold food in a Sistema container in a microwave: ALWAYS take the top off first. DO NOT attempt to cook anything in a Sistema container.>> While the Sistema containers are nominally "freezer safe", they are very brittle when "freezer cold". Do not drop them, and allow them to warm up a little before you try to open them.INTERIOR MEASUREMENTS of the container's I've purchased>> 101-ounce rectangular: 8 1/2" wide X 6" deep X 4" tall---top the same as "67.6 oz container">> 67.6-ounce rectangular: 8 1/2" wide X 6" deep X 2 1/2" tall---top the same as "101 oz container">> 15.2-ounce sandwich boxes: 5 1/4" X 5 1/4" X 1"---top same as "40-ounce lunch container">> 40-ounce lunch container: 5 1/4" X 5 1/4" X 2 1/2" tall---top the same as "15.2 oz sandwich box container"USES> I have 4 101-oz containers, 2 67.6-oz containers, and 6 sandwich containers. Together this make up a "group picnic kit">> The 101-Oz makes a great bread box. I use them for bread and chips.>> The 67.6-Oz makes a great cookie box. I use them for potato salad, and cole slaw.>> The 15.2-Oz is great for sandwiches. I use them for sliced cheese and lunchmeat.> Click on “Stoney” just below the product title to see my other reviews, or leave a comment to ask a question.