m303Why Choose the M303? Lower Emissions Simplified Installation Minimal Lifecycle Maintenance. Gallery. Description. The M&J Valve Model M-303 is an advanced desn slab gate valveBÖHLER 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