Product Description LDR 317 MCO-34 3/4-Inch Galvanized Merchant Coupling. Galvanized Malleable Fitting. Hydrostatic Tested. rating, 150 PSI. Galvanizing meets ASTM A-123 - hot dip process. Lifetime Limited Warranty. From the Manufacturer LDR 317 MCO-34 3/4-Inch Galvanized Merchant Coupling. Galvanized Malleable Fitting. Hydrostatic Tested. rating, 150 PSI. Galvanizing meets ASTM A-123 - hot dip process. Lifetime Limited Warranty.