Metal-Technik Prism Roller The pile roller is the best solution for uniform compaction and compacting of forage piles made of green fodder and maize. This reduces the risk of harmful mould and good quality silage, which reduces feed losses on the farm. The shaft can be filled with water, which will increase its weight by max. 1200kg in total giving 2920kg. The rings of the shaft squeeze up to 15 cm into the pile.