The appearance of regrowth?

Some customers report that, with regular use, hair grows back thinner and more sparsely over time.

We have no hard data to back that up, though. In fact, with the exception of waxing, no hair removal treatment has any robust evidence supporting any change in the density and thickness of hair grows following removal.  

Magic Crystal works by gradually wearing down the surface layer of the hair, using a process called micro-cuticle-abrasion.

There's no plucking and no cutting. Each hair is ultimately worn to a fine point right at the skin surface. This almost eliminates the risk of ingrown hair which typically results from the hair regrowth from beneath the surface.

The fine tip also significantly reduces the appearance of regrowth, especially compared to shaving which leaves a large cross-section of hair to grow back.