The RVB312 is Ronco's B-312 L.D. - a 53 gallon light-duty fresh water tank, and the second molding in the book at exactly this capacity. That duplication is deliberate: 53 gallons is a workhorse size, and Ronco cuts it in more than one shape so the tank conforms to the bay instead of the bay being rebuilt for the tank. If the first cut of this capacity does not drop into your compartment, this one may.
The resin is translucent natural polyethylene with FDA approval for potable water - fill it, put a light behind it, and the waterline is your gauge. Fittings are not part of the molding; Ronco spin-welds or thread-installs them per order at the locations you mark. That makes the drawing the first tool of the installation: print it below, mark supply, vent, and fill against the coach's plumbing, and finalize the positions in the on-page fitting planner.
It ships at 103 lb from Tustin, California, where Ronco has molded RV tankage since 1974 - same resin and same fitting bench as the marine line, walls specified for the gentler duty an RV bay imposes.
Cross-check the same capacity in other footprints in our RV water tank category - the RV68W is a third way to hold this much water - or survey everything on the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.