This cartrage holds insert RNGN-32 in the correct geometry for surfacing Cast Iron and Aluminum with the RNGN Round, 2 sided inserts.  This cartridge uses CBN Diamond for Cast Iron, and PCD Diamond (Single Sided usually) for Aluminum.  If the aluminum has ANY steel or cast inserts, you need to run our Bi-Metal Cartridge, whch has a speical CBN Diamond insert with custom special geometry.