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

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

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