The vehicle using the giant suppressor is an M109G 155mm self-propelled howitzer at an artillery range in Germany. The steel construction allows for it to be lifted into position and used when firing at a 30-degree elevation. But it cannot be attached to the turret, because tests showed it affected recoil and harm the turret barrel.
The holes on the silencer are kept as small as possible to keep the decibel levels lower, which is most effective behind and in front of the suppressor. The total cost of the construction is $100,000.
Silencers can reduce artillery noise by as much as 20 decibels, which may not seem like much, but is the difference between listening to your television and listening to your blender.