Raphael is a model and personal trainer from Brazil. I love his ass and that fantastic tan line.
Some prefer not to see tan lines, but I love 'em. They frame and highlight the private, the personal, the vulnerable. The tan line says to a man's lover, "this is for your eyes only; you alone are privileged to savor and enjoy this part of me."
They also remind me of the more "innocent" era of erotica, when men didn't bronze every square inch of their bodies on tanning beds. The porn of my youth was filled with images of gorgeous men sporting tan lines, so I imagine that's why I find them both erotic and preferable.