I watched one of their videos, specifically the VIVID AQUARIUMS TANK REPAIR one, and it concerned me about their technique of using their orbital sanders. The gentleman using the orbital sander was sanding only using the edge of it which is actually more damaging than using it flat with the surface. Using it that way creates an extremely uneven surface which can cause a wavy distorted view through the acrylic. Ideally you'd want to level it over a larger surface area to keep everything close in relative thickness. For those tough areas where there are really thick scratches, that's where spot-sanding treatment comes into play. Don't get me wrong, there are many ways to achieve the same result. However, I just wouldn't do it the way that's depicted in their video.