Check out the rad guards from Enduro Engineering and Moose (made in the same place I presume). These are a "wrap around" design that protect the rads very well from impacts (especially from the side) via a fairly rigid mounting system vs. the Flatland style which isn't as strong but provides better protection from sticking stuff into the rad from the front. BUT be warned that the front protection can cause decreased airflow that can be a factor depending on your riding style; to be avoided if you prefer tough low speed terrain. I have, unfortunately, tested the EE guards many times and can attest to their protection. I suppose that it's still possible to harm a rad with the EE guards but the impact would be so severe that a busted rad would be the least of your problems. BTW I came VERY close to sticking a branch through a rad once so the Flatland style (available from many sources) has it's merits; depends on what you want. I have seen "rad braces" on other bikes and I consider them to be mostly useless; too flimsy to do any good most of the time. I have no idea why to moto guys use these; a waste of money IMHO.
). The EE don't provide any frontal protection. Both will do the job, but I've had sticks wedged between the shrouds many times, so it's nice to know the front is protected.