These bars are a relatively recent development and have two versions. First the ZIPP Contour Bar 2007 is a road style, all carbon drop handlebar using cutting edge technology, great aero design, light weight, strength and carefully designed fit and function. There's an aerofoil top section with no round sections anywhere; this also gives a comfortable grip whereever you place your hand.
There is also substantial damping of high frequency vibration to provide comfort and the hook portion of the bar gives the right wrist angle. Its available in 31.8 mm diameter, in 42cm, 44cm, 46cm widths. Weights from 220gm to 230gm and drop is 149mm with 85mm reach.
Secondly there is the Zipp Contour SL Handlebar which is a stage racer's bar with comfort, great ergonomics, stiffness and aero design balanced together for all day use. There's an aerofoil top to fit your hand on long climbs while at the same time hiding cables.
The hook portion is oval to give a natural hand fit and the bar can still be used in a sprint as it is stiff enough. It comes in sizes: 40, 42, 44, 46 at a weight of 190g (42cm), clamp Diameter: 31.8mm. Available drops are: Ergo Bend, Traditional Bend, Short-Shallow Bend.