Screws into the original Purolator oil filter head or DB5 to DBS 6 with full flow conversion head (the STD DB5 to DBS 6 head uses a cast in thread)

we made this because a Swiss owner cleared us out of heads & nuts

They are made to give more oil flow' than the original nut as its been found there are restrictions in flow as originally made

For DB2 to DB4, these use a 3/8" bsf thread

For DB5 to DBS 6, these use a 3/8" unf thread.