There's a sin in this syntax:
Here's the problem: "Paperbacks" is the subject of the first phrase, which means the possessive "yours" in the second phrase must refer back to it. "Without breaking your paperbacks" surely isn't what the copywriter intends, although that's the only conclusion, grammatically, we can draw.
"Without breaking your back" would make sense, but there's no "back" in the sentence. Asking the reader to extract "back" (singular part of the human anatomy) from "paperbacks" (plural inaminate objects) is unreasonable and unfair.
Or are we being asked to extract "paper"?
Bottom line: If I have to work this hard to decipher a single sentence of ad copy, how hard will I have to work at mastering the Sony Reader itself?
P.S. Yes, there's a footnote after "350 paperbacks." The fine print reads: "Based on average un-illustrated eBook file size of 1.1 megabytes. Actual file sizes vary by digital book title."
P.P.S. This ad is part of a new Sony Electronics campaign featuring celebrities with whom I'm supposed to be on a first-name basis but don't even recognize. I finally figured out that "Peyton" is Peyton Manning, the football player, and "Justin" is Justin Timberlake, the singer. I have no idea who the bookends (so to speak) are or why I should care about any of these people's endorsement of an e-reader.