SFI-Rated Chrome-moly Steel Flexplate works with 6-Bolt convertor 4L80E/4L-85, 168-Teeth, internal balance for big block Chevy Vortec 8100. These flexplates are engineered to handle extreme duty applications and designed to take the punishment of today's high horsepower engines. Ring gears are precision welded to meet SFI specifications, utilizing robotic machinery and cold-welding process.