Tannoy - Ferrofluid for 1" tweeters

I just researched a bit again and it seems the original Tannoy stuff like this:

Tannoy Ferrofluid Syringe 7900 0604 150uL - Speaker Exchange

has the following properties:
150 uL (.15 ml)
921 APG
Gauss 165
Viscosity 200

Did not find 921 APG but 821 APG again from ferrotec:

But the question remains how to get this stuff here in Germany and how to apply the right amount..

I mean there are so many tweeters with this problem so I don´t really get why there is not more activity in this respect..