Allows the use of exhaust systems with 18 mm O2 sensor bungs to be used with late model bikes with 12 mm O2 sensors Reduces the 18 mm O2 bungs to 12 mm O2 bungs found on select '10-'15 models Wiring harness comes pre-assembled with connector pins Made in the U.S.A.. ADAPTERS 02 SNSR 18/12MM