These pans won't rust! The pads are reusable and there is no need to melt sticky wax. The covers close up for the day. The economy pan measures 10" x 7" and is perfect for the beginning dissection project, such as earthworms, small frogs, clams or grasshoppers. The standar pan measures 11.5" x 7.5" and is perfect for general use and medium sized specimens, such as perch, frogs, and crayfish. The deluxe pan measures 12.75" x 9" and is excellent for larger specimens, such as fetal pigs, bull frogs, and star fish.