These fitting were designed and  manufactured  for Holley Dual Feed Carburetors, to fit inoto stock adapters or fittings that allow you to remove the stock adapters and screw right into the carburetor fuel bowls.

Fit into Holley Carburetors
P/N     5170         -6 AN male to 7/8-20 male thread blue ( 2pcs)
P/N     5175         3/8" hose to 7/8-20 male thread clear ( 2pcs)
P/N     5180         -6 AN male to 7/8-20 male thread clear ( 2pcs)
P/N     5190         -8 AN male to 7/8-28 male thread blue ( 2pcs)
P/N     5200         -8 AN male to 7/8-20 male thread clear ( 2pcs)
P/N     5210         -8 AN male to 7/8-20 male thread 2" lg. blue ( 2pcs)