The all-welded steel hull of the 2S1 is divided into three compartments: driver's at the front on the left, engine to the right of the driver and the turret at the rear. The welded turret, which does not overhang the side of the hull, has a well-sloped front and sides with the commander seated on the left, gunner in front of and below the commander and the loader on the right. The indirect sight is mounted in the roof of the turret, forward of the commander's cupola with the direct sight being mounted to the left of the main armament. A long stowage box is often mounted on the left side of the turret and there is a large door in the rear of the hull, hinged on the left side. The rear door has a single firing port in the center. The suspension system is similar to the MT-LB multi-purpose tracked vehicle's and consists of seven road wheels with the drive sprocket at the front, idler at the rear, but no track-return rollers. An unusual feature of the 2S1 is that the suspension can be adjusted to give different heights, which is of particular use when the vehicle is being transported by tactical transport aircraft. The 2S1's main armament, designated the 2A31, is a modified version of the 122-mm D-30 towed howitzer. The ordnance is fitted with a fume extractor and muzzle brake and is held in position when traveling via a lock on the hull glacis plate which is operated by remote-control by the driver. A power rammer and extractor are fitted to the folding guard rail to enable a higher rate of fire to be achieved and to permit loading at any angle of elevation. A maximum sustained rate of fire of 5-8 rds/min can be obtained with a sustained rate of fire of 70 rounds for the first hour and, of the 40 122-mm projectiles normally carried, 32 are HE, six smoke and two HEAT-FS. Of the 40 rounds of 122-mm ammunition carried, 16 are in standby stowage on the left and right of the sidewalls. When in action, ammunition would normally be used from outside the 2S1 system and fed to the crew inside via a ramp. One of the two ammunition members outside the vehicle is connected to the vehicle intercom and would fuse the projectiles before they are passed into the vehicle. The remaining 24 projectiles and charges are stowed near the loader's position with the empty cartridge cases being ejected outside the turret. The HE projectile has a maximum range of 15300-m. Other ammunition types available include leaflet, HE/RAP (range of 21900 m), armor piercing high explosive, flechette, and chemical projectiles. Standard equipment includes infra-red night vision lights and an NBC system. It is fully amphibious, being propelled in the water by its tracks. Any water that enters the hull during amphibious operations is removed via the exhaust outlet using the bilge pump. Whilst afloat only 30 rounds (projectiles and charges) are carried. (Known to the West as the M-1974?)