Hailstorm in the context of "BM-21 Grad"

The BM-21 "Grad" (Russian: БМ-21 "Град", lit. 'hailstorm') is a self-propelled 122 mm multiple rocket launcher designed in the Soviet Union. The system and the M-21OF rocket were first developed in the early 1960s, and saw their first combat use in March 1969 during the Sino-Soviet border conflict. BM stands for boyevaya mashina (Russian: боевая машина – combat vehicle), and the nickname grad means "hail". The complete system with the BM-21 launch vehicle and the M-21OF rocket is designated as the M-21 field-rocket system and is more commonly known as a Grad multiple rocket launcher system.

In NATO countries the system, either the complete system or the launch vehicle only, was initially known as the M1964. Several other countries have copied the Grad or developed similar systems. In Russian service its intended replacement is the 9A52-4 Tornado. Many similar 122 mm MLRS systems are made by different countries based on the BM-21 Grad.