Single Sided PCD Conical Insert to Surface Aluminum in Positive Rake Cartridge.  SUPEIROR FINISH ON ALUMINUM! 
 
These inserts are designed for supreme finish and are test proven to compete with leading inserts.  Do not use this insert on any steel or any iron in the aluminum head or block.    Performance CBN has a special insert just for Bi Metal applications which is a cartridge and insert combination. 
 
RNGN 32 = 3/8"Diameter X  1/8" Thick
RNGN 43= 1/2"Diameter X  3/16" Thick