If a cuckoo clock marvels you with a cute little bird that pops out every hour, Matching Pair of Singing Bird Pistols will surprise you even more. The only publicly known pair of their kind created by master craftsmen Frères Rochat, Christie’s is all set to bring the mechanical marvel under the hammer. The matching set of two crafted in gold and enamel comes studded with gems, diamonds and pearls. Estimated to fetch between HK$20 million and 40 million ($2.5 million to 5 million), the gun is quite a marvelous piece of work. When you take a shot, a bird comes through the double barrels, pivots, flutters its wings and tail, opens its beak to sing and then goes back in again. Quite a highlight this piece will make when the auction bell rings.