At 19g for a set, these brake pads are the lightest metallic pads available from Shimano. They backing plates are made of titanium to save weight. In comparison, the resin G02A and G03A pads ...
Shimano XTR CS-M970 lockring
Aluminum lockring that comes with XTR CS-M970 9 speed clusters - weight 5g. Standard steel lockrings are around 15g so switching to an alu version will save you an easy 10g.