I recently bought a pair of brake calipers off fleabay. The rear brake has recessed nut/mounting as it should, but the front caliper came with the older standard nut (and no, the seller didn't mention this little detail).

Can I just buy something off fleabay like this (New Bike Bicycle Brake Recessed Brake Nut 30mm BE13162 | eBay), or do I need to buy the entire screw and bolt pair (which I cannot find anywhere).