Bitspower fittings; sizes

[Formular VI]

Can someone explain sizes on these( BitsPower) fittings.
I find it very confusing Bitspower fittings are often given in fractions of inch,( which is bad enough if your used to metric) whereas Tubing diameters are mostly quoted in millimetres !!!

I was looking on Youtube at :
Singularity Computers Client Build 12 Build Log: Part 2 at approx. 20:16 / 28:46


Where he is using, EK-HD Solid Tube 12/16mm, and also using Bitspower fittings.

But on trying to order Bitspower Fittings from Performance PC I was told these fittings would not fit this tubing????
Am I missing something here ?

I would be very grateful if someone can explain

 

[SuB]

Most tubing is given in both fella.. to my knowledge bitspower fittings are all 1/4bsp for fitting to things (the standard size) and rigid acrylic is pretty standard now, they fit the regular one.

 

[Shaw]

He's using Bitspower rotaries and EK HD 12/16mm fittings. Bitspower only make fittings for 10/12mm acrylic.