Very light, double butted stainless wheelsmith spokes, Wheelsmith handbuilt, XTR hubs mean highest quality, titainium freehub, each ball of the bearing is selected by computer for exact size match for most precision ballbearing hub available in the world, no other company goes through the extent of quality control shimano does with ballbearing hubs!
NONE! PLEASE keep in mind that Mavic 517 and X517 are CROSS COUNTRY rims not freeride/downhill and should be used as such, at 395 grams a rim they are incredibly strong FOR X-COUNTRY race wheels,, they are the best non-disc x-country race wheels available, lightest rims and top of the line spokes laced with alloy nipples to the best hub that the largest and most sucessful company in the world of bicycling has produced,,,well,, you do the math!
You must be aware of the type of riding you do when selecting any wheel, these are not built to withstand hucking, use your best judgment when buying, if you intend to go dropping off 3'-4'drops then you will be dissapointed with the flat spots in your wheelset but if you want fast wheels these are hands down THE BEST FOR THE $$$$$$ BAR NONE!!