View a demonstration video here.
 
This mallet is only light when compared to its daddy - de Grandhomme. Instead of the grand 14mm shaft, these mallets use a 12mm, and instead of a large core of solid Jarrah hardwood, it's a large-ish sized disc of cork. The combined weight of this core and wrapping materials necessitated a longer shaft of 38cm to find an appropriate balance.
 
That recipe makes a pretty big mallet by anyone's definition. The only reason we call it "light" is because it isn't Jarrah.
 
Core: Cork
Shaft length: 38cm
Shaft diameter: 12mm