Snow guards help prevent the dangerous movement of snow and ice on metal roofs. When installed correctly, evenly throughout the entire roof area, snow guards safely hold the snow in place. By preventing the snow and ice from ever moving to begin with, these simple plastic snow guards can help stop dangerous snow slides. Many building owners realize that snow guards even pay for themselves the first time they save the gutters, car or dog. ly hold the snow in place. The snow and ice never has a chance to crash off the roof.