Very little is known about why this singular prototype Double-Split was made in steel, beyond the assumption that the management of Lange wanted to experiment with a lighter case for the relatively beefy watch, only made in heavier gold and platinum cases. This watch was produced in 2006 and represents an unbelievably cool and, until now, totally unknown instance of one of modern horology’s greatest chronographs. When you consider the fact that Patek’s 5004 was made in 50 examples in steel, and one sold at 270,000 CHF, and this is the only Double-Split in such a metal, you realize just how special this watch is.