This is a frame with foundation.
The frame is made of 4 pieces of wood, called bars, stapled together: top bar, bottom bar, and two side bars. They come in deep, medium, and shallow. The frame size should match the box size.
Frames come and with or without foundation. Foundation is inserted in grooves in the top and bottom bars. The foundation gives bees a place to build honeycomb. We like plastic foundation because it holds up best in the extractor. Wax foundation is not sturdy enough on its own in a deep frame.
Notice that the side bar to bottom bar joint above is designed so the side bar is stapled to the bottom bar, rather than the bottom bar being stapled to the side bar. This prevents separation when the frame is heavy with honey.
The side bar to top bar joint below has two staples: one from above and one under the ear. This helps prevent the frame from separating, as shown below.
Sometimes we add side support staples to our personal frames. They are not absolutely necessary with plastic foundation; however, if you choose to scrape old (dark) or damaged wax comb from the foundation, staples will keep the foundation securely in the frame. (It is a good idea to scrape off old wax about every 3 years, or 1/3 every year, to prevent some bee diseases.) Also, the staples help keep foundation and wax in the frame when extracting honey.
Be sure the communication holes in the foundation go at the bottom of the frame.