FR66s vs Ikeda IT-407 CR tonearms

What are the 345 & 407 made from? The construction overall looks closer to FR64fx & FR66fx than to FR64s & FR66s.

This review says 345 & 407 are made from stainless steel:
https://www.stereophile.com/content/listening-128

This review says they're made from "a combination of aluminum, zinc-bronze, stainless steel and brass":
https://www.dagogo.com/ikeda-sound-labs-it-407cr1-long-tonearm-review/

The anti-skate provision by 345 is an enigma.

It looks identical to the one in FR64fx & FR66fx.

I use the term "new" Ikeda because Mr Ikeda is clearly no longer with the current Ikeda which is making the new Ikeda tonearms and offering service for FR arms.

It’s the same company that Osamu Ikeda founded after Fidelity Research went bust in the 1980s, but I think he himself retired recently and there is a new owner.

He is here said to have been 35 when he started Fidelity Research in 1964. That would make him ~89 this year.
http://www.hi-fiworld.co.uk/vinyl-lp/30-turntables/165-eat-forte-turntable.html?start=2

He is here interviewed in 2009 saying he is 83 and was still building tonearms and cartridges, like he had been doing for 60 years. That would make him ~92 this year.
http://www.theabsolutesound.com/articles/high-end-audio-in-japan-part-five-analog-from-ikeda-sound-lab/ 

He is here in 2012 said to have retired and IT Industries is now managing the company:
https://www.dagogo.com/ikeda-sound-labs-it-407cr1-long-tonearm-review/

Regarding the material, the Ikeda Labs website is particularly uninformative, only saying "Hybridization of the material of the main part" (Google translation), which seems to indicate that it's not pure stainless steel or aluminum.

http://www.islabs.co.jp/it345cr1.html

Now the ''curious'' anti-skate provision by 345&407. This is

not even similar with FX kind. The forgotten ''child'' the 245

however has similar to FX anti-skate provision.

I have an FR64fx and an FR64s, but have not compared directly with 345 & 407. However, from every picture I can find, the anti-skate in 345 & 407 looks very similar to the FR64fx. Here are pictures of 245 and the anti-skate looks quite different:
http://www.hifido.co.jp/sold/?KW=&G=0302&LNG=E&O=1500&L=50&C=07-30498-90074-00

I can't think of what aging or maturing would do to silver and why it would sound better. There has been improvement in casting, at least for copper, since the introduction of FR64s, so it might well be that current silver is better made. 

Here is a picture of FR64fx anti-skate:
https://oshiete.xgoo.jp/_/bucket/oshietegoo/images/media/b/1229872_5497e546339ce/M.jpg

And here is IT-407:
http://img.ukaudiomart.com/uploads/large/1747444-ikeda-it-407-with-fidelity-research-b60-base.jpg

The function of the knob with the finger screw is to adjust the lever so that it is level when the cartridge is at the beginning of the record. This allows the anti-skate force to be calibrated regardless of how the tonearm is rotated horizontally and to decline at the same rate as the cartridge moves across the record.