Are these four models on separate stands? Or are all of the models attached to a single stand?

Hello. In response to your question, the four models are attached to one stand. They are removable, of course, for ease of demonstration. Please let me know if we can be of further help. Sincerely, Edward at Lake Forest Anatomicals

Are these models flexible and able to demonstrate range of motion of the joints?

Thank you for your inquiry No, these are rigid models. You will need to review the following SSM Series Premium or Budget Functional Models as below. Sincerely, Edward 2400 Shoulder, Functional, SSM 2405 Foot/Ankle Functional, SSM 2410 Knee, Functional SSM 2415 Elbow, Functional, SSM 2420 Hand/Wrist Functional, SSM 2425 Hip, Functional, SSM 2440 Shoulder, Budget Functional Series 2441 Hip, Budget Functional Series 2442 Knee, Budget Functional Series 2443 Elbow, Budget Functional Series 2445 Set of 4 LFA #2440-2443