Book excerpt: (Music Sales America). Notecrackers are handy little packs of facts, tips and entertainment on musical topics. They give instant reference to things like chords and music theory as well as musical trivia and jokes, making them perfect pocket-sized gifts. Each pack is 1-1/8 high x 3-1/4 wide and features drilled laminated pages with one fact or theory per page so you can quickly flip through the pack.