In my experience the Yamaha Acerbis ones are very good and work well, saving you replacing levers if the bike falls over of course. They are very tough and also good looking but I fear that Yamaha may have stopped having them made so you can try and fine some in existing dealer stock OR get some Acerbis ones of course, but I could not find my way around their web site.

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(Now sold on, sob) 2011 Blue XT660X with gold wheels, was 26,500 km.
Engine mods: K&N Stage 1 filter, DNA Stage 2 filter, snorkel removed, Kev fuel mod fitted.
Plus: smoked Puig screen, Yam aluminium sump guard, Yamaha / Acerbis handguards, Givi Trekker aluminium side cases, Leo Vince X3 cans plus Kev front fork mod and Fender Xtender. Just fitted Michelin Road Pilot 3 tyres.

SOLD the XTX for a Super Ten 1200. And just bought a Raptor 700 so staying on here for some tips....