Of course, just like cables, mains stuff, digital cables, etc there will be unbelievers, and that's fine. However, I've just got some in, after being shown the effect a/b (between two copies of the same disc, one with green pen, one without, and also doing before/after listening on a couple of discs, while wearing my sceptic hat (subsequently eaten)). This stuff works. There are sound physical reasons why it should (and I'm saying that as someone who specialised in semiconductor material and device theory), and the effect is definately audible. How would I characterise it? Cleaner... clearer, more focused. There is more definition throughout the frequency range, with more textures, weight and punch in the bass and greater transparency in the mids.