FWIW...just remember that the threads in the Festool products accept BSPP, also known as G-thread. BSPP is British Standard Pipe Parallel, it is not a taper pipe thread.
Here is the Festool QD coupling and Festool fitting compared to the black Husky Hi Flow fitting. Notice the straight (parallel) threads on the silver Festool fitting versus the taper threads on the Husky fitting.
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Here is the business end of both of the fittings, they are the same & are interchangeable for use in the Festool QD coupling.
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I needed the taper pipe thread fitting (black Husky Hi Flow) to convert a Milwaukee (Gast) vacuum pump for use with the Festool Vac Sys.
In this photo you can see the standard Festool fittings in the Festool products and because they have parallel threads, they seal against the white polymer seals.
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