They are 7.5mm radial caliper spacers (go between the caliper and fork leg) and allow the use of 320mm front discs (just happen to have a pair of brand new RT discs lying in the garage that came with a set of 17" wheels I briefly used on my old r1200gsa tc).
Just need a set of four M10 x1.25 x 73mm bolts and before anyone asks why , the answer is because I can