I was going to install this on my GS500f but then sold it.
Size is SB7100 - SB7100 # M7 X 1.0 1.38, (35.15)
I guess it'll work for other uses too.

It's a speed bleeder for speed bleeding your brakes / whatever.
Brand New condition, still in the envelope...
Comes with the hose, cost me more than $20

Thanks, price firm at $15