shell fragments. The front of the hull provided protection from up to 20 mm armour-piercing discarding sabot (APDS) rounds. Later variants increased protection up to 30mm APDS, in response to the 30 mm autocannon armed BMP-2 and the development of top attack cluster bomblets. The Marder is a relatively conventional design, with the driver sitting at the front left side of the hull with the engine to his right. The driver has three day periscopes mounted in a hatch that opens to the right. The center periscope can be replaced by a passive night vision device. Behind the driver is a seat for a single infantryman. In early versions of the Marder, this man had a hatch that opened to the right and a periscope that could be rotated through 360 degrees. This hatch was removed in the 1A3 variant onwards. In the center of the hull is the two-man turret, which holds the commander on the right and the gunner on the left. Only the commander is provided with a hatch. The commander has eight day periscopes for all round observation and the gunner has three. The primary sighting system is the PERI-Z11 sight, which has either 2× or 6× optical magnification. From version 1A2 on, there is an additional thermal sight with 2x and 8x magnification. To the rear of the turret is the troop compartment, which can hold six infantry men, sitting back to back facing outwards along the center of the hull. The Marder is capable of fording in up to 1.5 meters of water unprepared. It can be fitted with a kit allowing it to ford water up to 2.5 meters deep. The vehicle is powered by an MTU MB 833 Ea-500 six-cylinder liquid-cooled diesel engine which delivers approximately at 2,200 rpm. The cooling radiators are mounted at the rear of the hull, either side of the exit ramp. The engine is coupled to a Renk four speed HSWL 194 planetary gear box, with four forward and four reverse gears. The transmission also provides steering and braking via a stepless hydrostatic unit, which transmits power to two drive units mounted at the front of the hull. The vehicle carries 652 liters of fuel, giving it a road range of around 500 kilometers. Early Marders could achieve a road speed of 75 km/h in 4th gear, but the extra armour of later vehicles reduced this to