"There are 3 large circles on the bottom of these storage boxes that result in 3 narrow grooves about a coffee mug in diameter being molded in the bottom, so after buying 7 boxes I am disappointed to find parts stuck solid in the bottom and actually resorting to using a knife to pull flats out from the gap. My advice is only to buy if all you have is standard Lego bricks as they are not suitable for 'technic' or creative sets."