signature of the IFV. Another crew safety measure is that the main fuel tanks are placed outside of the vehicle hull itself, mounted heavily armored within the running gear carriers. While this may pose a higher penetration risk to the tanks, it is unlikely that both tanks will be penetrated at the same time, enabling the vehicle to retreat to a safer position in case of a breach. There is also a collector tank within the vehicle, which acts as a reserve tank in case of a double tank breach. A large number of change requests and bureaucratic requirements drove up costs. Sensors and situational awareness The Puma offers improvements in situational awareness. The fully stabilized 360° periscope (PERI) with six different zoom stages offers a direct glass optic link to either the commander or the gunner. Since this is an optical line, it had to be placed in the turret center, one of the reasons why the main cannon is mounted off-center on the turret. Via an additional CCD camera the picture from this line can also be fed into the on-board computer network and displayed on all electronic displays within the vehicle. Besides that, the periscope offers an optronic thermal vision mode and a wide-angle camera with three zoom stages to assist the driver, as well as a laser range finder. The whole array is hunter-killer capable. The commander also has five vision blocks. The gunner optics, which can be completely protected with a slide hatch, are mounted coaxially to the main gun. The gunner has a thermal vision camera and laser range finder (identical to those on the PERI) and an optronic day sight, rounded off with a glass block. The driver has three of vision blocks, as well as an image intensifier and a display for optronic image feeds. The passenger cabin has a hatch and three vision blocks on the rear right side of the vehicle, one of them in a rotary mount. The rear cabin also has two electronic displays. All in all, the Puma has an additional five external cameras at its rear in swing-mounts for protection while not in use. Apart from the glass optic periscope view directly accessible directly by the commander and gunner and indirectly via the CCD camera, all optronic picture feeds can be displayed on every electronic display within the vehicle. The provisions for the rear cabin enable