Friction material. Get some good pads/shoes...... not the chain store crap.
One of my close friends has a shop and has done that scarebird front disc
kit a couple of times so that the original rims could be maintained.
1) the bracketry is pretty wimpy, he copies the originals but fabs thicker brackets
2) mishmash of caliper and rotors are used..... some folks don't care, some do.
The mechanic 5 years down the road will wonder what's on there though.
ex-Global West GM
As the drill sergeant said, "I taught you everything you know. I didn't teach you everything I know."
"Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so."
- Douglas Adams