Used for plumbing fuel lines to filters. Purchase separately for all Racor MA fuel/water separators to match existing or new fuel lines.500 MA Series Fitting Selection Chart Fitting for 500 Series (Old Style)TypeModel9/16"-18 Male to 9/16-18 MaleStraight1087899/16"-18 Male to 9/16-19 Male90 Elbow1087719/16"-18 Male to 1/4"-18 FemaleStraight4180209/16"-18 Male to 3/8"-18 FemaleStraight1088139/16"-18 Male to 5/16"-3/8" hoseStraight4662199/16"-18 Male to 5/16"-3/8" hose90 Elbow466201Fitting for 500 Series (New Style)TypeModel3/4"-16 Male to 1/4" NPT FemaleStraight3317533/4"-16 Male to 3/8" NPT FemaleStraight3317613/4"-16 Male to 1/2" NPT FemaleStraight3317793/4"-16 Male to 9/16"-18 JICStraight3317203/4"-16 Male to 9/16"-18 JIC90 Elbow3316883/4"-16 Male to 3/4"-16 JICStraight3317383/4"-16 Male to 3/4"-16 JIC90 Elbow3316963/4"-16 Male to 3/8" Beaded hoseStraight*12577163/4"-16 Male to 3/8" Beaded hose90 Elbow*3317873/4"-16 Male to 1/2" Beaded hoseStraight*331811