the 0450102 is the designated lead-free replacement for the 0393040

With inside dimensions of 7-1/16" L x 4-1/8" H x 2-1/4" D for the ring base

Key Benefits: Precision Compatibility: Designed specifically for Lochinvar Knight (KBN080-500) and Armor (AWN/AWL) series water heaters and boilers

What is the difference between a standard regulator and a modulating valve like the MR410

Johnson Controls P67AA-1 Pressure Control Freon the 0450102 is the designatedLow Pressure Control, DPST, Opens on Pressure Drop, 3 to 30 Psig Scale Range, 32 to 140 Degree Temperature Range, 1 1 2 to 20 Psi Differential, Angle Barbed Fitting Connector, 50 Psig Maximum Overpressure P67AA 1 is identical to 2366 251 This item does not qualify for free shipping.