Dont buy them – they don't fit!!! Take it from me and my bitter, biter experience. Chewed through a set of XTR rings on M970 crankset, went to get some replacements and can only get Shimano ones to fit, so cranks in the garage due to the price – silly stupid amounts of cash.
I've had a falling out with CRC over this, having bought some Middleburn ones that didn't fit and sent them back, also some TA one's that didn't fit – the BCD is fine (as indicated) it's that on the XTR ones the shape of the bolt hole is rounded slightly so that aftermarket chainrings don't fit