Fidelity Research FR-64x

@chakster  I have both the heavy and the medium weight.

Heavy 245g 2.5cm long
Medium 175g 2.0cm long

Thanks, so i'm fine
I was worried because the black W-250 (250g) for "fx" version is 30mm long, but i think it's different material. 

Anyone can tell me the exact weight of the original N-60 arm stabilizer nut ? I have FR brochure scan where i can see N-60 + additiona metal washer on the picture, the mass of the combo is 430g.

But what is the mass of the N-60 (without metal washer) ?
Is it possible that the mass of the N-60 is 370g ?

It means the washer weight is 60g, is that true ?

Would be nice to check, because the N-60 normally shows up for sale without washer. I’m gonna use N-60 for 64fx tonearm.

No users of Fidelity-Research N-60 arm stabilizer nut here ?
My collection completed, now i have N-60 and B-60.
-The N-60 stabilizer nut will be on 64fx
-The B-60 base on fr64s 

I have the same set up as you. In my experience there is a clear sonic gain with the N-60 stabilizer nut. The added mass seems to benefits the 'bottom end' of the sonic spectrum and makes the whole presentation somewhat more relaxed. This can be observed with both the 64s and 64fx arms. Sonically the B-60 base does the exact same thing, with the added convenience of VTA on the fly.

If anyone is interested, I have a spare N-60. It's a replica, but then again this is just a piece of machined stainless steel. No washer, but the same weight and same dimensions as the original. The only difference is that the original has a sticker with the model number.