I have the largest size and they weigh 1.8 ounces for the pair on my scale.
I just leave my hiking shoes on when I cross a stream so I haven't tried the light shoes to cross. I gave a pair to a friend, however, and he said they worked fine for crossing streams.
They have, of course, crossed streams within my hiking shoes but I don't think that counts.
They are thicker and stiffer than typical shoe inserts. I like that because it gives my feet a little more protection from sharp rocks than a lighter insert would. By the way, I put the mesh on the downside when I use them as shoe inserts.
I tried to use the "insert image at cursor" feature for the hot link to the shoes but it doen't work with links to websites. Glad you were able to connect to it.