The Shilka ZSU-23-4 [ZSU = Zenitnaya Samokhodnaya Ustanovka - Anti-aircraft Self-Propelled Gun] is a Self-Propelled Anti-Aircraft Gun (SPAAG) featuring a prominent radar dish that can be folded down mounted on a modified PT-76 chassis. ZSU 23-4 Shilka, is capable of acquiring, tracking and engaging low-flying aircraft (as well as mobile ground targets while either in place or on the move). Employed in pairs 200 meters apart, 400 meters behind battalion leading elements, it is commonly used to surpress ATGM launch sites, such as TOW vehicles. The armament consists of four 23mm cannon with a maximum slant range of 3,000 meters. Ammunition is normally loaded with a ratio of three HE rounds to one AP round. Resupply vehicles carry an estimated additional 3,000 rounds for each of the four ZSUs in a typical battery. Recent (October 1997) information details ZSU-23-4 updates/modernization being offered by the Ukrainians that include: a new radar system replacing the GUN DISH radar, plus a sensor pod believed to include day/night camera, and a laser rangefinder; and mounted above radar/sensor pod is a layer of six fire-and-forget SAMs, believed to be Russian SA-18/GROUSE.