The cadmium zinc TElluride Radiation Imager, or TERI, is an instrument to space-qualify large-volume 4×4×1.5 cm3 pixelated CdZnTe (CZT) detector technology. The CZT’s anode is composed of a 22×22 array of pixels, whereas the cathode is planar. TERI contains four of those crystals with each pixel having an energy range of 40 keV up to 3 MeV with a resolution of 1.3% full-width-at-half maximum at 662 keV all while operating in room temperature. As the detectors are 3D position sensitive, TERI can Compton image events. TERI is fitted with a coded-aperture mask, which permits imaging of low-energy photons in the photoelectric regime. TERI’s primary mission is to space-qualify large-volume CZT and measure its degradation due to radiation damage in a space environment. Its secondary mission includes detecting and localizing astrophysical gamma-ray transients. TERI is manifested in the Department of Defense’s STP-H10 mission for launch to the International Space Station in early 2025.