Dekorra Products Boulder Rock, 56-Inch by 42-Inch by 30-Inch, Riverbed Brown Price: $700.00 (as of 02/01/2024 23:40 PST- Details)

Durable – UV protected will not fade in the sun or crack in cold weather.
Ideal Applications: Septic manholes up to 36″D; Backflow assemblies 2″D; Pumping system assemblies, constant pressure well equipment and tanks
Keep in mind, colors will vary a bit from one rock to the next.