The perfect tool for easy backyard queen rearing without grafting and lots of specialized parts. A deep hive body is divided into three separate nucleus colonies with different entrances on the front and two sides. Pull a frame with a queen cell from your hive, add a frame or two of food (both honey and pollen) and one or two frames worth of young bees shaken from brood frames. The nurse bees will care for the developing queen and brood till the virgin queen flies out to mate. Once you have a laying queen you can use her for requeening weak colonies or making up nucleus colonies.
Take queen cells from your strongest hives and let them mate with your local drone population. Local queens are generally the best queens you can have in your hives, especially where winters are long and cold.