How Flat is Flat? DLM sells, services and calibrates a wide range of precision granite surface plates to meet every specification. A leader in the domain of surface plates with superior overall flatness and measurement repeatability, DLM continues to excel in the field of metrology. DLM has earned its reputation by providing unparalleled calibration services in the aerospace, military and automotive industries among others. Performed on-site or at DLM's facility, each certified calibration is efficiently executed by highly trained technicians with years of qualified experience. Due to a growing industry demand, a fully equipped mobile unit is readily available to perform onsite calibration and resurfacing.