Had the following reply from Seas today ...
Quote
"These are custom made tweeters for Meridian, so we are not able to give out any information about these. When that is said, I think any ferrofluid should work fine."
So I have managed to get someone to send me some APG L11 which should arrive next week and hopefully will be enough to do both the H1054 and the spare H539.

I will keep you posted and take lots of pics.

Rgds
Stuart

Linn LP12, Ittok LV11, Arkiv, Linn Kairn as a phono stage, MPmax 221, DSP6000's, WiiM Pro streamer.