Weighted boot liners?

I have the equifit boots and was looking at their page.

http://www.equifit.net/index.php?option=com_hikashop&ctrl=product&task=show&cid=2692&name=weighted-t-foam-liners-for-luxe-hind&Itemid=229&category_pathway=23

What do these do?

Thank you!

Help build leg strength, encourage the horse to lift its legs more over a fence. I see how they’d be beneficial in training, but I don’t think (?) you can show with them.

Plenty of room for them to be abusive if used in a improper way, just like the TN walkers. IMO if used and not overdone its not much different than switching to a aluminum or composite shoe right before a show.

I just thought they were interesting.

Has anyone ever used them?