I have three pair of brand new, never-installed, Shimano M70 v-brake pad inserts. These are designed for rim brakes, either v-brake or cantilever style, and fit with all Shimano cartridge style brake sets (and some non-Shimano styles as well). See the list of compatible models below.
Ordered these for my bike but I got the wrong style and shipping them back to the manufacturer will be too expensive to be worth it.
I have three boxes, all three of them are brand new and come with the original packaging, which includes the right and left brake pad and two pins used to hold them in the brake housing. $5 for a pair (one box). $15 if you'd like all three boxes (three pair of brake pads).