S&W Mod 41 Weights

[rbert0005]

I saw some counterweights for a Mod. 41 that looked like a bi-pod.
There was one with the "wings" about 4" and another with 6" ones.

They slide onto the end of a 7"bbl. and you slide small weights on the "struts"

Any ideas? A value of these would be nice, as well.

Thanks,
Bob