This aluminum adapter has 12x1.5mm male threads on one end and an 8AN male (3/4-16 thread, 37° flare) on the other. Note that the metric end is hollow, without a sealing surface. You must use a 12mm Aluminum Crush Washer (Part No. 3278-M12, sold separately) with this fitting.
This adapter fits the outlet side of the popular Bosch "044" (FP200) fuel pump or the newer Bosch FP200-7 Fuel Pump. Anodizing color may vary from photo. Sold individually.