I was in a shop today, and on a hunch I compared the brake pads for the old Shimano XTs (only decent brake they've made to date, IMO), Grimeca System 8 (or 12, whichever one was relabled and sold as the previousy mentioned XT) and the new Hope Mono M4. They are in fact the exact same pads and retention springs. Very smart move on Hope's part, tapping into relatively good and more importantly pre-existing pad availability in Joe Shmoe's Random Bike Shop with a brake that has just recently come to market from a brand with relatively low small parts availability.