The corresponding RayTracingSubMeshFlags value for opaque Materials.
To maximize ray tracing performance on the GPU, RayTracingSubMeshFlags.Enabled combined with RayTracingSubMeshFlags.ClosestHitOnly is recommended. This flags combination will ensure that any hit shaders are not invoked during acceleration structure traversal when rays hit opaque geometries.
Additional resources: RayTracingAccelerationStructure.CullInstances.