Maxitrol 1-1/4in straight flow thru regulator rv61-1 1/4, up to 2,500,000 btu maxitrol’s original straight-thru-flow design meet your needs for high capacities at low inlet pressures. Models are designed for 1/2 psi rate pressure under the ansi standard for gas pressure regulators. They are main burner only, non-lockup type. Use only where downstream controls can operate at line pressure.