Not quite dead flat, this bar has an almost imperceptible 5 degree sweep. The clamping area is a "road" 26mm but of course it still is still compatible with flat bar controls. The lack of curvature actually makes it look wider than it really is: it is only 4cm wider than the very obviously "street riser bar" B260AA so in practice there probably aren't many gaps in the traffic one can go and the other can't.
 

• Construction: Aluminium alloy
• Handlebar clamp diameter: 26.0mm
• Grip area diameter: 22.2mm
• Width: 520mm
• Weight: 205g (approx)