Acker-Stone 2-205-01-06-502-53-00000 6" x 9" 6cm Onyx FM Umbriano Chamfer. UMBRIANO® paving stones feature a patented 360 degree integral sealing process, Acker-Lock Plus, that protects and shields against ground moisture, reduces efflorescence, decreases everyday surface stains, and is easy to clean. These pavers feature a randomized color application which ensures no repeating patterns over large surfaces, offering you an unparalleled level of uniqueness.