OML is pleased to offer tombstones of the highest accuracy and outstanding dimensional repeatability. Milling and finish machining of the steel and aluminum tombstones are completed with high precision machines using the ......OML is pleased to offer tombstones of the highest accuracy and outstanding dimensional repeatability. Milling and finish machining of the steel and aluminum tombstones are completed with high precision machines using the highest quality tools available. All tombstones are quality controlled using a coordinate measuring machine.