Are they a puzzle or a model? While we're still not sure which application will provide the most enjoyment, we absolutely love these detailed, reasonably priced anatomy models that you can put together, take apart, and build again! Each model is made up of approximately 30 pieces (although some may already be assembled in the packaging) and each stands about 5" tall. The pieces are all painted realistically, include small display stands, and come with very basic assembly guides. The heart model features four "doors" that swing out and allow you to see the inside chambers of the heart, while the eye model comes complete with all the muscles that hold the eyeball in place and the lacrimal gland too. The head model shows one side of the head with muscle, and one side of the head with bone, while the skull shows how the brain fits inside the skull and the spinal cord as well. The human body (torso) model features removable organs, a segment of the spinal cord and back muscles, removable ribs and a bisected head for a look at several body systems. The ear model depicts the inner, outer and middle ear.