The Semnan Missile Complex includes a ballistic missile test range and production facility reportedly built with substantial Chinese assistance. [1] Iran began producing the Oghab unguided artillery rocket at Semnan in 1987 with the goal of producing 600 to 1,000 such rockets per year. [2] The plant also produces the solid-fueled artillery rocket Nazeat, Shahab-I missiles, and might be involved in the production of Zelzal rockets. [3] The Iranian Space Center and associated launch facilities are located in the vicinity of the site.

Sources:
[1] Anthony Cordesman, The Military Balance in the Middle East (Washington, DC: Center for Strategic and International Studies, 2004), p. 488.
[2] Anthony Cordesman, The Military Balance in the Middle East (Washington, DC: Center for Strategic and International Studies, 2004), p. 488.
[3] Iran's Ballistic Missile Capabilities: A Net Assessment, International Institute for Strategic Studies, 2010, p. 49; Yonah Alexander and Milton M. Hoenig, The New Iranian Leadership (London: Praeger Security International, 2008), p. 178.