Not as great as it sounds (but still worth having). Works out at 90p off an Explorer series map, normal price £6.79. What's that?... "90p isn't 40% of £6.79!", I hear you say. Well no, but it is 10% of £8.99 (the RRP), and dash4it sell at 30% off, £6.79 30 plus 10 = 40% off That's a fine bit of sophistry.