The HPA Steel Slip Fitting Adapter attaches to your engine's rubber macro line. A replacement part. Male ends attach to QD adapter sold separately. The steel end slips onto your macro line for a pressurized seal. This is not the 6mm size, but will work fine with 6mm macro line once pressurized. 1/4" steel end to male 1/8" male end HPA adapter.If you lose the one that came with your Polarstar engine, this is a drop-in replacement.