According to Fars News Agency:
The Iranian Defense Ministry on Sunday supplied large numbers of long-range ground-to-ground missile launchers to the Islamic Revolution Guards Corps (IRGC).
Addressing the ceremony, Vahidi said that the delivery of such a large number of missile launchers demonstrates the Islamic Republic of Iran's self-sufficiency in designing and building the strategic system and shows the Iranian Armed Forces' massive firepower and their ability to give a crushing response to the enemy.There had been suggestions that a shortage Transport Erector Launcher (TEL) vehicles might be a limiting factor on Iran's ability to provide adequate chances of survivability for its missile forces in the event of an aggressor first strike. If so, this latest claim indicates an effort to address this need. Additionally, it could suggest or purposely indicate an increase in Iranian MRBM stocks. Even so, in the above photo provided by Iranian media, slight variations in these TELs are evident, suggesting non-standardization and some level of improvisation, in addition to slight universal changes interpreted as refinements in erector construction.
Below are examples of TELs exhibited in the past. Note the slight variations in design and construction:
Photos: PressTV and Military.ir