Prisma is a cast-iron grating for covering drainage channels that are subjected to heavy loads. Aside from its functionality, it offers an appropriate appearance for an urban environment. The homogenous surface has a fine structure of interwoven facets that reflect the light in a variety of ways. The locking device is placed on a second level to avoid disturbance of impression given by the continuous pattern. A high-quality cataphoretic coating in anthracite grey completes the overall appearance.