There's one thing that puzzles me about the SP market, and that is why so many of the books come in such odd dimensions - the kind you never see in the commercially published stuff. I'm talking specifically about paperbacks here. The two main choices with commercially published paperbacks are Trade and Mass Market. Mass Market are falling by the wayside now, but they are still a very traditional and recognizable size (17cm x 11cm). Tradebacks, now far more common, are slightly larger (19.5cm x 12.5cm). Why then are the choices in the SP world so varied? Admittedly I haven't looked into the area of SP very thoroughly, but I don't think I've ever seen anywhere that offers these traditional and familiar sizes, with the smaller Mass Market size seemingly being a definite no-no.