For years, I have been using the industry standard pour in pads, Equithane's Equi-pak, particularly the copper-sulfate version.
Although they are tremendously useful, they are also a bit if a pain to use functionally.
Now we have a fairly new product from Castle Plastic to compete with Equi-pak. It's a much more reliable and easy product to use.
I especially use these pour in pads when applying wedge pads. The reason is that the pads often raise the frog away from the ground and therefore reduce or eliminate the function provided by ground contact.
These pictures aren't really telling the story or showing the mechanics like they should, but the point is that this is an interesting product that I have been trying out with success. I'm glad there is an alternative.