This listing is for an extremely rare and unusual piece of scientific and aerospace research history: a RHESUS Project ESOP High Fidelity Mockup, also referred to as a "Monkey Box." This apparatus was built by CARRAR S.A. in St-Germain-en-Laye, France, likely as part of a program involving biological studies in space or high-stress environments. Manufacturer: CARRAR S.A., France Project: RHESUS ? ESOP High Fidelity Mockup Assembly Drawing: 1121-ME-00-00-000 Serial Number: 005 This high-fidelity "Monkey Box" mockup originates from the RHESUS Project, a European initiative likely tied to early biomedical research involving rhesus monkeys in aerospace conditions. During the Cold War and well into the space race, both the U.S. and international partners like the European Space Agency (ESA) conducted critical biological experiments using primates to simulate the effects of spaceflight on living organisms. This unit, built by Carrar S.A. (France), represents a mockup used for engineering, training, or procedural validation ? possibly for launch or transport procedures. It features aerospace-style hardware, latching mechanisms, cable interfaces, and reinforced viewing windows typical of space program equipment. These types of devices were never made for the public ? they were produced in extremely low numbers, used internally by agencies, and typically destroyed or archived after use. This is a rare survivor and a conversation-starting piece of space biomedical history.