I finally decided to get rid of the plastic food storage containers that get stained and never look good again.  These all look great and go in the microwave just fine.  They are a sturdy glass. The lids secure on them well so I don't have to worry if it tips over in my lunch bag.   I did have one of the small rectangle ones warp a little on the bottom when it was hot but then it went back to normal once it cooled.   I like to microwave my old fashioned oatmeal in the morning and it is good that I can watch the water start to bubble up and stop the microwave before it boils over.