The BM-21 Grad is a Russian truck-mounted 122 mm multiple rocket launcher, developed in the early 1960s. Several other countries have copied it or developed similar systems. The BM-21 122 mm multiple rocket launcher (MRL) system entered service with the Soviet Army in 1963 to replace the aging 140 mm BM-14 system. It consists of a Ural-375D 6X6 truck chassis fitted with a bank of 40 launch tubes arranged in a rectangular shape that can be turned away from the unprotected cab.In 1976, the BM-21 was mounted on the newer Ural-4320 six-by-six army truck.