A complete high density polystyrene langstroth hive (less frames) consisting of:
Langstroth floor and varroa mesh
4 x Medium bodies
Feed plate cover
Hive entrance reducer
Running your bees on medium depth frames gives the benefits of having the same depth frames throughout the hive plus significantly lighter loads to lift. this hive is designed to be run with the lower two hive bodies containing the brood and then two more medium depth hive bodies above a queen excluder used as supers for the honey crop. The 20 medium depth frames under the queen excluder give almost exactly the same brood volume as a colony running on brood and a half on 22 national frames - without the problem of having different sized frames with all the complications that can bring when an artificial swarm is carried out. See the poly hive use page for advice on how to introduce bees on full depth frames to this hive, whether langstroth or national. These instructions also cover subsequent management of the colony and their transformation to a complete colony on medium frames. No more bad backs!
you can find all of the langstroth complete hives here.