m303PHI M303 630 Mortise Lock Body, 03 Function, Satin Stainless Steel Finish. Product Type: Exit Device PartAccessory. Model: PHI M303 630 LHR, M303 630 RHR. PHI_Precision-2000BÖHLER M303 EXTRA is a corrosion-resistant, martensitic chromium steel with very good toughness, corrosion resistance, good wear resistance and improved machinability and polishability. Compared to 1.2316, BÖHLER M303 EXTRA