Wonderful bookcases from Wisteria

Breezing through Wisteria catalogue this am, I came across these wonderful open bookcases.
What do I love about them? Large bookcases can look heavy when they have a solid back, but open them up and it's a new ballgame. I also like the heaviness of the wheels which contrasts the fly-away lightness of the shelves..... This design also comes in a console.