BM-21 "Grad"

The BM-21 "Grad" (БМ-21 "Град") is a launch vehicle of the Soviet 122 mm multiple-launch rocket system developed in the early 1960s. BM stands for 'combat vehicle' (Russian: Boyevaya Mashina); grad means 'hail'. In the West, the system was initially known as M1964.

http://en.wikipedia.org/wiki/9K51_Grad