The Airbrake goggles' have a generous field of vision and modular design, which has allowed Oakley to develop a special Race-Ready Roll-Off system that uses a wider roll of film for better visibility in the mud than the standard Airbrakes.
The removable film canisters are built into special outriggers on either side of the lens, making the whole design sleek and compact. Two thin sections of transparent wire lift the film off the lens, so there's no threat of it sticking when it rains. Vision is undistorted too.
The only drawback with this system is that you have to get the film lined up perfectly for it to work without snagging. For this reason, we'd strongly advise against using aftermarket films, which lack the special alignment tab found on Oakley's version.
Blasting through puddles, the Airbrake's field of vision and comfy fit, combined with the ease of clearing your vision, make them a real pleasure to wear.
These goggles aren't exactly cheap, but they're only £30 more than the regular Airbrake goggles, so it makes sense to buy the roll-off version for muddier riding. That's said, it'd take a little of the sting out of the cost if there was more than one roll of film in the box.