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 with aluminium backing plates weigh only 10g. For normal use I prefer the resin G02A pads but have recently bought some G03A pads to try.
I've bought these G04Ti pads to use on my bikepacking bike for a long (1000km+ trip) which has over 20,000m of climbing and descending. It will be interesting to compare their performance to that of the G02A resin pads.