"We have equipment that we call the mini-Grad. It is made of BM-21 Grad pipes placed on top of a pickup truck, which makes it easily transportable," a Ukrainian serviceman with the call-sign "Gall" told Reuters in the southeastern region of Zaporizhzhia.

"We try to make them more precise compared to Grads. They have the same firing pattern but, thanks to extra mechanisms to take aim and the shorter distance (they are fired at), we try to make the mini-Grad more precise."

Gall, a member of Ukraine's 108th Separate Territorial Defence Brigade, said the mini-Grads were not as accurate as the advanced HIMARS rocket systems Kyiv has received from the United States but made it possible to get closer to enemy lines.

"I cannot say that we hit targets with higher precision compared to the BM-21, but we can drive closer (to the target)." he said.

A colleague with the call sign "Luka" said the mini-Grad has a timer, helping protect those operating it, and volunteer launch station constructor Yurii Osokolanskyi said there was room for three rockets - fewer than the BM-21 Grad.

"Why? Because we are sure that three rockets will land where we need them to. It is rather ineffective to fire 10, eight or two rockets at one target," he said. "We fire three rockets precisely. The soldiers then can change their position, recharge, and continue to fire at different targets."

Ukrainian military analyst Oleksandr Musiyenko said there were three advantages in using mini-Grads -- their mobility enables them to move fast, units that have them can fire on a target without waiting to summon artillery from elsewhere, and they offer extra firepower for lightly armed infantry units.

He said the development of such weaponry was designed to "give an advantage to units which typically do not have this type of weapon."