Plastic is very clear, thick, solid, and sturdy. Lids are snug and certainly give an airtight feel. The only thing that feels cheap, and the reason I removed a star, is the tabs/clips on the underside of some of the lids. The levelers, spoon, and terra cotta have clips on the lids so you can store them out of the way of the contents - one of the clips on the flour container arrived to me broken. No qualms with the products themselves, just surprised by one coming broken, especially considering how well packaged everything came.