In our head-to-head test of 15 sanding discs, the 3X discs proved among the most aggressive and durable while still delivering a near-flawless finish at both 180- and 220-grit.
…
Our only beef: The dark-printing-on-blue-background on the discs' backs makes it difficult to read the grit number on the discs, especially after they've been used for awhile.