I bought this about a year ago when my band was in a rehearsal space with wooden floors. I was shaking everything and it was such a small room that it would resonate at a weird frequency. This really helped clean up my tone in the room and get rid of all that low end rumble. This was under an Ampeg 8x10. We are now in a space with concrete floors and it's no longer necessary.
It's in great shape. Looking locally for Chicago right now because shipping it would be a little silly.
Looking for $50 OBO