m303BÖHLER 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 EXTRAPHI 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-2000